Evening primrose, borage and GLA oils

Q: What are evening primrose oil, borage oil and GLA?

Evening primrose oil and borage oil are oils pressed from seeds. Both contain gamma-linolenic acid (GLA), an omega-6 fat. GLA is the part most studied, and some products are sold by their GLA content.

Q: Are these oils omega-3?

No. NCCIH describes evening primrose oil as containing omega-6 fatty acids, including GLA. Fish oil is the omega-3 oil, with EPA and DHA. They are different fats.

Q: Do they help eczema?

No. A Cochrane review of 27 trials (1,596 people) found oral evening primrose oil and borage oil no better than placebo. A 12-week trial of borage oil in 140 children and adults found the same.

Q: Do they help PMS or breast pain?

Reviews found no benefit over placebo for either. For breast pain, a review of 13 trials found evening primrose oil no different from placebo or other treatments. For PMS, two reviews found no benefit.

Q: Do they help menopause hot flashes?

The evidence is mixed. A 2024 review found milder hot flashes under six months but no change in how many or how long. A 2025 review found no significant change in number but shorter hot flashes. Both call the evidence limited.

Q: Do they help rheumatoid arthritis?

Small older trials suggested less joint pain and swelling, using much more GLA than usual products. Cochrane calls the evidence moderate but NCCIH says insufficient. Do not stop arthritis medicines without a doctor.

Q: Is borage oil safe for the liver?

Borage plants contain alkaloids that can harm the liver. Memorial Sloan Kettering says to use only borage oil certified free of them, and that people with liver problems should avoid borage. One commercial oil tested in a laboratory had alkaloids below the detection limit.

Q: Can I take them in pregnancy or while breastfeeding?

Memorial Sloan Kettering says borage should not be used in pregnancy or breastfeeding. NCCIH says evening primrose oil may be safe but the evidence is not conclusive. A 2022 review does not recommend it for starting labour. Ask a midwife or doctor.

Q: Do they interact with blood thinners?

Possibly. The Cochrane eczema review cites a study suggesting more bleeding with evening primrose oil in people on warfarin. This is from small studies. Ask a pharmacist or prescriber.

Q: What are the side effects?

NCCIH says evening primrose oil is generally well tolerated; the most common problems are stomach pain, nausea and diarrhoea. Memorial Sloan Kettering lists headache, belching and loose stools with borage oil.

Oenothera biennis and Borago officinalis seed oils (gamma-linolenic acid) · also called EPO, starflower oil, GLA, aceite de onagra, aceite de borraja

Evening primrose oil and borage oil are seed oils that supply GLA, an omega-6 fat. They are widely sold for skin, hormone and joint complaints. Reviews found no benefit for eczema, breast pain or PMS, and the evidence for arthritis and hot flashes is limited. The main cautions are liver-toxic alkaloids in borage (choose certified-free oil), pregnancy, and possible extra bleeding with blood thinners. Ask a doctor or pharmacist first.

General information, not medical advice. Last substantive update October 26, 2026 · Not medically reviewed. A named clinician has not signed off on this page. How this page is made

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About Evening primrose, borage and GLA oils

Evening primrose oil and borage oil are GLA-rich seed oils. Large reviews found no benefit for eczema, breast pain or PMS. Evidence for arthritis, nerve damage and hot flashes is limited. Borage has a liver-alkaloid caution, and both oils may raise bleeding risk with blood thinners.

What these oils are

Evening primrose oil comes from the seeds of a plant native to the Americas. Borage oil comes from the seeds of the borage plant. Both contain GLA, an omega-6 fat. According to Memorial Sloan Kettering, borage oil is about 25% GLA and evening primrose oil about 10%.

They are not omega-3 oils like fish oil. The body makes GLA from the common omega-6 fat linoleic acid, so GLA is not an essential nutrient. See the omega-6 page and the fish oil page for the contrast.

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What the research shows

The best-tested uses are the ones with the clearest negative answers. A Cochrane review of 27 trials found no eczema benefit, and a 12-week borage trial agreed. A review of 13 trials found no benefit for breast pain, and two reviews found none for PMS.

Small older trials of GLA suggested less pain in rheumatoid arthritis, using far more GLA than usual products. Two reviews of menopause hot flashes disagree on how long they last. A few single trials found lower blood pressure, fewer acne spots or better nerve tests, but none has been repeated. NCCIH says there is not enough evidence to support evening primrose oil for any health condition.

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Borage oil and the liver

Borage plants contain pyrrolizidine alkaloids that can injure the liver. Memorial Sloan Kettering says the risk rises with length of use and total amount, and advises borage oil certified free of these alkaloids. It says people with liver problems should avoid borage.

In one laboratory analysis, a single commercial borage seed oil had alkaloids below about 200 parts per trillion. That is one sample, not a guarantee for any other product. Borage leaves and flowers eaten as food are different from the oil.

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Other sources of GLA

Blackcurrant seed oil is another seed oil that supplies GLA and was grouped with the two oils in the arthritis review. No USDA amounts of GLA in food were found in the sources read, so this page gives no per-portion figures. This page gives no amounts to take; ask a doctor, pharmacist or dietitian.

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At a glance

Traditional uses history, not proof

Evening primrose juices put on the skin and leaves taken for stomach and throat complaints by Native Americans
Borage oil used for sweating, coughs and inflammation, and as a GLA source

Studied for research

Source of GLA, high certainty
Eczema, evidence against
Breast pain and PMS, evidence against
Rheumatoid arthritis, low certainty
Menopause hot flashes, mixed
Diabetic nerve damage, low certainty
Acne and blood pressure, very-low certainty
Starting labour, mixed

Main compounds

Gamma-linolenic acid (GLA)
Linoleic acid
Dihomo-gamma-linolenic acid (made in the body from GLA)
Pyrrolizidine alkaloids (in borage; should be absent from certified oil)

Common forms

Soft-gel capsules
Liquid oil
Skin products (not covered by trials read)

Research links: 2013 Cochrane review: evening primrose and borage oil for eczema (27 trials) · 2003 BMJ trial: borage oil for eczema (140 people) · 2011 Cochrane review: herbal treatments for rheumatoid arthritis · NCCIH: evening primrose oil · Memorial Sloan Kettering: borage · Research Library · Genes & Biomarkers Library

What it is and its history

Accepted scientific name: Gamma-linolenic acid (GLA) oils: evening primrose oil (Oenothera biennis) and borage seed oil (Borago officinalis)
Naming authority: Oenothera biennis L. and Borago officinalis L. (GBIF accepted names)
Common names: Evening primrose oil, EPO (English); Borage oil, starflower oil (English); Aceite de onagra, aceite de borraja (Spanish)
Family or group: Two different plants whose seed oils both supply GLA. They are not related to fish oil.
Classification: Plantae > Tracheophyta > Magnoliopsida > Myrtales (evening primrose); Boraginales (borage) > Onagraceae (evening primrose); Boraginaceae (borage) > Oenothera; Borago > Oenothera biennis; Borago officinalis
Native range: NCCIH says evening primrose is native to North and South America and also grows across Europe and parts of Asia. Borage range was not given in the sources read.
Habitat: Not described in the sources read.
What it looks like: Flowers: NCCIH: evening primrose has yellow flowers that open at sunset and close during the day.; Fruit: Seeds are pressed for the oil.
Cultivation: Not described in the sources read.
Harvest and processing: Oil is taken from the seeds. How it is pressed or refined was not described in the sources read.
Look-alikes and adulterants: Name: Blackcurrant seed oil; Note: Another seed oil that supplies GLA; included with the two oils in some arthritis trials (Cochrane 2011).; Name: Fish oil; Note: Supplies the omega-3 fats EPA and DHA, a different fat family. Do not confuse EPO (evening primrose oil) with EPA.; Name: Borage leaf and flower; Note: Eaten as herb or tea; contains the liver-toxic alkaloids and is not the same as the refined seed oil (Memorial Sloan Kettering).
Sustainability and conservation: Not assessed.

Traditional use and history history, not clinical proof

Tradition or era	Documented use	Source
Native American use (evening primrose)	Juices of the stem and leaves were put on the skin for inflammation, bruises and small wounds, and the leaves were taken by mouth for stomach and throat complaints.	s-nccih-epo
Herbal and traditional medicine (borage oil)	Used to cause sweating, as an expectorant, against inflammation, to promote milk flow and stimulate the adrenal glands, and as an alternative source of GLA to evening primrose oil.	s-msk-borage

Traditional use shows how it was used. It does not show that it works or is safe today.

What is inside, and how it may work

What it contains and how those compounds act in cells and animals. Laboratory and animal mechanisms are not proven effects in people.

Main compounds

Compound	Family	Where it is concentrated	Activity studied	Level of evidence
Gamma-linolenic acid (GLA) PubChem 5280933	omega-6 fatty acid	Seed oil Memorial Sloan Kettering: about 25% of borage oil and about 10% of evening primrose oil.	The body can convert GLA to DGLA, a building block for inflammation-signalling chemicals. ^{21 22}	Human data
Linoleic acid PubChem 5280450	omega-6 fatty acid	Seed oil Not given in the sources read.	The parent omega-6 fat from which the body makes GLA; present in both oils (Memorial Sloan Kettering for borage). ²¹	Human data
Dihomo-gamma-linolenic acid (DGLA) PubChem 5280581	omega-6 fatty acid	Made in the body from GLA Not applicable.	Described as able to block the changing of arachidonic acid into leukotrienes and other prostaglandins (Memorial Sloan Kettering). ²¹	Lab
Pyrrolizidine alkaloids (amabiline, supinine, lycopsamine, intermedine and others)	plant alkaloids	Borage plant; should be absent from certified oil One commercial borage seed oil: below about 200 ppt (2013 laboratory analysis).	Liver-toxic in higher amounts (Memorial Sloan Kettering). ^{21 16}	Human data

Mechanisms, receptors and pathways

Target or pathway	Gene or receptor	What was found	Level
GLA to DGLA to anti-inflammatory signals	Not specified	Memorial Sloan Kettering says GLA can convert to DGLA, which can block the changing of arachidonic acid into leukotrienes and other prostaglandins, and that GLA can raise cAMP which suppresses TNF-alpha, a chemical linked to rheumatoid arthritis. This is a proposed pathway from lab work, not a confirmed effect in people. ²¹	Lab
Genetic variation in fatty acid desaturase	rs174537 (fatty acid desaturase region)	Memorial Sloan Kettering cites a study in which borage oil raised blood GLA and DGLA depending on genotype, which could explain why trials differ. We did not open that study. ²¹	Human data
Prostaglandins and the cervix	Not described	NCCIH says it has been suggested that evening primrose oil might help start labour by increasing prostaglandins. Studies have had inconsistent results. ^{22 8}	Author hypothesis

Absorption, metabolism and elimination

Absorption: Not described in the sources read.
Distribution: Evening primrose oil taken during breastfeeding raises the GLA level in breast milk (NCCIH).
Metabolism: GLA can be converted in the body to DGLA (Memorial Sloan Kettering).
Elimination: Not described.
Bioavailability: Not described.

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Isolated compounds versus whole extracts

Trials used different things: whole evening primrose oil, whole borage seed oil, blackcurrant seed oil, or purified GLA. Results from one cannot be assumed for another, and the amounts of GLA differ.

Nutritional composition

GLA is not an essential nutrient: the body makes it from dietary linoleic acid (Memorial Sloan Kettering and NCCIH describe the oils as sources). No USDA GLA values were found or read, so no per-portion amounts are given. GLA is also in a few other seed oils such as blackcurrant seed oil.

11benefits and uses looked at

22studies and sources checked

High certaintybest evidence rating found

9lab markers tracked in trials

1 high certainty2 mixed findings2 low certainty2 very low certainty1 not enough evidence3 evidence against

What was looked at

The 11 benefits and uses checked for Evening primrose, borage and GLA oils, each with how strong the evidence is. Tap one to open it.

A source of GLA, an omega-6 fatHigh certainty
Eczema (atopic dermatitis)Evidence against
Rheumatoid arthritis pain and joint symptomsLow certainty
Breast pain (mastalgia)Evidence against
Premenstrual syndrome (PMS)Evidence against
Menopause hot flashesMixed findings
Diabetic nerve damage (neuropathy)Low certainty
AcneVery low certainty
Blood pressure and body fat after menopauseVery low certainty
Starting labour and softening the cervixMixed findings
Inflammatory conditions overallNot enough evidence

Lab markers tracked in the studies

Eczema sign score (SASSAD)Tender and swollen joint counts in rheumatoid arthritisHot flash frequency, severity and durationBreast pain reliefNerve conduction and nerve function testsNerve pain score (0 to 10)Acne lesion countBlood pressure (systolic and diastolic)Bishop score (cervix readiness)

What is Evening primrose, borage and GLA oils good for?

The main studied uses and how strong the human evidence is for each. Most trials used capsules of one oil, and results for one oil may not apply to the other.

A source of GLA, an omega-6 fatHigh certaintyEvening primrose oil and borage oil are seed oils that supply gamma-linolenic acid (GLA). They are omega-6 oils, not omega-3 oils like fish oil. One cancer-centre page puts GLA at about 25% of borage oil and about 10% of evening primrose oil. EczemaEvidence againstA Cochrane review of 27 trials (1,596 people) found neither oil beat placebo for eczema. A 12-week trial of 140 people found borage oil no better than placebo. NCCIH agrees. Rheumatoid arthritis joint symptomsLow certaintySeven small trials of GLA oils suggested less pain and disability, but the trials were old, small and used much more GLA than usual products. NCCIH calls the evidence insufficient. Side effects were more common with GLA, though the difference was not statistically solid. Breast painEvidence againstA review of 13 trials (1,752 women) found evening primrose oil no better than placebo or standard treatments for breast pain. Premenstrual syndrome (PMS)Evidence againstTwo reviews found no benefit of evening primrose oil for PMS. Calcium had better evidence in one of them. Menopause hot flashesMixed findingsA 2024 review found milder hot flashes under 6 months but no change in number or length. A 2025 review found no significant change in number, but shorter hot flashes. Both call the evidence limited. Diabetic nerve damageLow certaintyA 1993 trial of 111 people found GLA slowed nerve changes over a year. Two newer trials were small, short or had no placebo-only group. One was funded by a supplement company. AcneVery low certaintyOne small 10-week trial of 45 people reported fewer acne spots with borage oil (and with fish oil). It is a single trial and has not been repeated. Blood pressure after menopauseVery low certaintyOne 6-month trial of 96 postmenopausal women with high blood pressure reported lower pressure and waist-hip ratio with borage oil plus vitamin E than with vitamin E alone. Starting labour and softening the cervixMixed findingsA 2024 trial of 96 women using a vaginal capsule found a higher cervix score and less oxytocin need. A 2022 review of 11 studies does not recommend it and found important bias. NCCIH says results are inconsistent. Inflammatory conditions overallNot enough evidenceA 2024 review of evening primrose oil trials in many inflammatory conditions found mixed results and no basis for strong recommendations.

Benefits, one by one

Each card is a research question, not a promise. Tap a goal to filter. Open a card to see the studies, doses and limits.

A source of GLA, an omega-6 fat

High certainty

Evening primrose oil and borage oil are seed oils that contain gamma-linolenic acid (GLA), an omega-6 fat. They are not omega-3 oils like fish oil. Borage oil is richer in GLA (about 25%) than evening primrose oil (about 10%), according to one cancer-centre source.

2 studiesSoft-gel capsules and liquid oil. GLA content differs between oils an…

Studies, doses and limits

What the trials found

NCCIH says the oil of evening primrose seeds contains omega-6 fatty acids including GLA. Memorial Sloan Kettering says borage seed oil is a rich source of GLA and linoleic acid and gives about 25% GLA for borage and about 10% for evening primrose.

Results

Both oils really do supply GLA. Supplying GLA is a description of the oil, not a proven health benefit.

Effect sizes as reported

No effect size applies: these are content facts.

Why this rating

High that the oils contain GLA (NCCIH, Memorial Sloan Kettering). It is not a trial result for any health outcome. The GLA content of any product depends on the oil and the maker.

Form and dose studied

Soft-gel capsules and liquid oil. GLA content differs between oils and products; see the label.

Who was studied

General population.

Limits

The percentages come from one patient-education page. Precise GLA content of products was not checked, and USDA does not list GLA for these oils in the sources we read.

Why researchers looked

People ask what these oils are and how they differ from fish oil.

Traditional use

Native Americans used juices and leaves of the evening primrose plant on the skin and for stomach and throat complaints, according to NCCIH. Borage oil was used in traditional medicine for sweating, coughs and inflammation, according to Memorial Sloan Kettering.

Proposed mechanism Established nutrition

The body can turn GLA into a related fat (DGLA) that is a building block for inflammation-signalling chemicals. This is the idea behind many of the studies (Memorial Sloan Kettering).

A proposed mechanism does not show that the effect happens in people.

Borage oil has its own liver caution; see the Safety tab.

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Eczema (atopic dermatitis)

Evidence against

Both oils were widely thought to help eczema because of their GLA. A large review and a good-sized borage trial found they work no better than placebo.

3 studiesOral capsules of evening primrose oil or borage oil.

Studies, doses and limits

What the trials found

Cochrane (2013) pooled 27 trials of 1,596 people (19 of evening primrose oil, 8 of borage oil). Evening primrose oil did not significantly improve eczema over placebo by patient rating (mean difference -2.22, 100-point scale) or doctor rating (-3.26). Borage oil also failed to beat placebo. A separate 12-week BMJ trial of 140 evaluable people found borage oil no better than placebo (difference 1.4 points favouring placebo, P = 0.45). NCCIH agrees.

Results

No benefit shown for eczema.

Effect sizes as reported

Evening primrose oil: -2.22 (95% CI -10.48 to 6.04) patient rating; -3.26 (-6.96 to 0.45) doctor rating. Borage oil trial: 1.4 points favouring placebo (-2.2 to 5.0).

Why this rating

Consistent negative findings from a Cochrane review and a large well-run trial. One review author had a link to a manufacturer (disclosed).

Form and dose studied

Oral capsules of evening primrose oil or borage oil.

Who was studied

Adults and children with atopic eczema.

Limits

Short trials (the 12-week BMJ trial was the longest). Long-term effects were not examined.

Why researchers looked

Eczema is a common reason people buy these oils.

Traditional use

Evening primrose oil has long been promoted for skin complaints.

Proposed mechanism Author hypothesis

The idea was that extra GLA would calm skin inflammation. Trials did not confirm it.

A proposed mechanism does not show that the effect happens in people.

Side effects were mild and similar to placebo in these trials.

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Rheumatoid arthritis pain and joint symptoms

Low certainty

Some older trials of GLA oils found less joint pain and swelling in rheumatoid arthritis. Reviews call the evidence limited, and the amounts in the trials were far higher than in usual products.

4 studiesGLA from borage, evening primrose or blackcurrant seed oil; one trial…

Studies, doses and limits

What the trials found

A 2011 Cochrane review of herbal treatments found seven trials of GLA from evening primrose, borage or blackcurrant seed oil that suggested less pain (-32.83 points on a 100-point scale) and less disability, with more side effects (20% versus 3%) that were not statistically different. In a 24-week trial of 37 people, 1.4 g a day of GLA in borage seed oil cut tender joints by 36% and swollen joints by 28%, while the cottonseed-oil placebo group did not improve. A 56-person trial using 2.8 g a day of purified GLA found 14 of 22 responders versus 4 of 19 on placebo. NCCIH says the evidence for evening primrose oil in rheumatoid arthritis is insufficient.

Results

Possible benefit in small, older trials; not established.

Effect sizes as reported

Pain -32.83 points (95% CI -56.25 to -9.42); disability -15.75% (-27.06 to -4.44); responders 14/22 vs 4/19 (P = 0.015).

Why this rating

Cochrane rated it moderate; NCCIH calls it insufficient. The trials are small, mostly from the 1990s, mix three oils, and used much more GLA than usual products.

Form and dose studied

GLA from borage, evening primrose or blackcurrant seed oil; one trial used purified GLA.

Who was studied

Adults with active rheumatoid arthritis.

Limits

Small trials, very high amounts, mixed oils, poor reporting. Rheumatoid arthritis needs medical treatment; do not stop medicines.

Why researchers looked

GLA is thought to dampen inflammation, and arthritis is a common reason people try the oils.

Traditional use

Borage oil has been promoted for arthritis in herbal practice (Memorial Sloan Kettering).

Proposed mechanism Mechanism hypothesis

GLA can be converted to DGLA, which may block the making of some inflammatory chemicals. This is a lab-level idea, not a proven effect in people.

A proposed mechanism does not show that the effect happens in people.

Do not stop or change arthritis medicines without a doctor. See bleeding and liver notes on the Safety tab.

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Breast pain (mastalgia)

Evidence against

Reviews found evening primrose oil no better than placebo or standard treatments for breast pain.

2 studiesEvening primrose oil capsules.

Studies, doses and limits

What the trials found

A 2021 review and meta-analysis of 13 trials with 1,752 women found no difference from placebo, topical NSAIDs, danazol or vitamin E in pain relief, and no extra side effects. NCCIH says it is probably not more effective than placebo.

Results

No benefit over placebo shown.

Effect sizes as reported

No difference in the number achieving pain relief.

Why this rating

Consistent: a meta-analysis of 13 trials and NCCIH agree.

Form and dose studied

Evening primrose oil capsules.

Who was studied

Women with breast pain.

Limits

Trial quality is not described in the abstract.

Why researchers looked

Breast pain is one of the most common reasons women are offered the oil.

Traditional use

Marketed for women's health complaints.

Proposed mechanism Not tested

No mechanism was tested in these reviews.

A proposed mechanism does not show that the effect happens in people.

Side effects were not more common than with placebo.

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Premenstrual syndrome (PMS)

Evidence against

Two reviews found no benefit of evening primrose oil for PMS. Other options, such as calcium, had better evidence.

3 studiesEvening primrose oil capsules.

Studies, doses and limits

What the trials found

A 2009 review of 62 products found trials for only 10 and no evidence of benefit from evening primrose oil. A 2011 review of herbs for PMS (10 trials included) found no effect different from placebo for evening primrose oil. NCCIH says evidence is insufficient.

Results

No benefit shown in the reviews read.

Effect sizes as reported

No pooled effect size (trials too different to combine).

Why this rating

Two systematic reviews agree, but they cover few evening primrose trials and are more than 10 years old.

Form and dose studied

Evening primrose oil capsules.

Who was studied

Women with PMS or PMDD.

Limits

Old reviews; small trials; the abstracts do not give the number of evening primrose trials.

Why researchers looked

PMS is another common reason for use.

Traditional use

Marketed for women's health complaints.

Proposed mechanism Not tested

No mechanism was tested.

A proposed mechanism does not show that the effect happens in people.

No major health risks were seen, but too few people were tested to be sure.

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Menopause hot flashes

Mixed findings

Reviews disagree. A 2024 review found milder hot flashes under 6 months but no change in how many or how long. A 2025 review found no significant change in number but shorter hot flashes. Both call the evidence limited.

3 studiesEvening primrose oil capsules.

Studies, doses and limits

What the trials found

Thevi 2024: severity was lower than placebo when used for under 6 months; frequency and duration did not differ; compared with black cohosh, hot flashes were more severe at 8 weeks. Larki 2025 (6 trials, 450 women): about 2 fewer hot flashes a day, not statistically significant; duration shortened significantly; intensity not significantly changed; evidence graded moderate to low. NCCIH says evidence is insufficient.

Results

Mixed: the two reviews disagree on duration, and both say more research is needed.

Effect sizes as reported

Daily hot flashes -2.13 (not significant); intensity -0.19 (not significant); duration significantly shorter (2025 review).

Why this rating

Two recent reviews give different answers for duration; trial numbers are small and quality graded moderate to low.

Form and dose studied

Evening primrose oil capsules.

Who was studied

Menopausal women with hot flashes.

Limits

Small trials; the abstracts give few numbers.

Why researchers looked

Many women look for alternatives to hormone treatment.

Traditional use

Marketed for menopause symptoms.

Proposed mechanism Not tested

No mechanism was tested.

A proposed mechanism does not show that the effect happens in people.

Mild nausea and headache were reported.

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Diabetic nerve damage (neuropathy)

Low certainty

A 1993 trial found GLA slowed nerve changes in mild diabetic neuropathy. Newer trials are small, short or had no placebo-only group. Evidence is limited.

3 studiesGLA 320 to 480 mg a day in the older trials; evening primrose oil 1,0…

Studies, doses and limits

What the trials found

Keen 1993: 111 people with mild neuropathy took 480 mg GLA a day for a year; all 16 nerve measures changed more favourably than placebo, 13 significantly. Won 2020: 100 people, 320 mg GLA a day versus alpha-lipoic acid for 12 weeks; both lowered pain and GLA was noninferior for pain, but there was no placebo-only group. Gholami 2025: 66 people, evening primrose oil for 4 weeks; the twice-daily group had the biggest pain fall.

Results

Possible benefit; the evidence is limited and mostly older or small.

Effect sizes as reported

Keen: 13 of 16 measures significantly better. Won: pain difference between GLA and alpha-lipoic acid -0.65 (95% CI -1.526 to 0.213). Gholami: pain 5.96 to 4.63 (twice daily).

Why this rating

One year-long trial from 1993 and two small newer trials with design limits (no placebo arm; 4 weeks). One trial was funded by a supplement company.

Form and dose studied

GLA 320 to 480 mg a day in the older trials; evening primrose oil 1,000 mg once or twice a day in the 2025 trial.

Who was studied

Adults with type 2 or mild diabetic neuropathy.

Limits

Small, short or no placebo-only group. Diabetes and nerve damage need a doctor's care.

Why researchers looked

Nerve pain is a common diabetes problem and GLA oils have been tried for it.

Traditional use

Borage oil has been promoted for diabetic neuropathy (Memorial Sloan Kettering).

Proposed mechanism Author hypothesis

The idea is that GLA supports the fats in nerve cells. This has not been confirmed in the trials read.

A proposed mechanism does not show that the effect happens in people.

Do not replace diabetes medicines. Ask a doctor first.

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Acne

Very low certainty

One small 10-week trial reported fewer acne spots with borage oil (and with fish oil). It is one study, and another review lists acne among uses without shown effect for evening primrose oil.

2 studiesBorage oil containing 400 mg GLA.

Studies, doses and limits

What the trials found

Jung 2014: 45 people with mild to moderate acne took borage oil with 400 mg GLA, omega-3 fish oil, or nothing for 10 weeks. Inflammatory and non-inflammatory lesions fell significantly in the GLA and omega-3 groups, and skin staining showed less inflammation.

Results

Promising but based on one small trial.

Effect sizes as reported

Significant fall in lesions; numbers not given in the abstract.

Why this rating

A single small trial with three groups; the control type is not described in the abstract.

Form and dose studied

Borage oil containing 400 mg GLA.

Who was studied

People with mild to moderate acne.

Limits

Very small; short; no repeat trial.

Why researchers looked

GLA is sometimes sold for skin complaints.

Proposed mechanism Author hypothesis

The trial authors suggest anti-inflammatory effects; this was not proven.

A proposed mechanism does not show that the effect happens in people.

No severe side effects were reported in this trial.

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Blood pressure and body fat after menopause

Very low certainty

One 6-month Brazilian trial reported lower blood pressure and waist-hip ratio with borage oil. It is a single trial and the comparison group also got vitamin E.

1 studiesBorage oil 1,000 mg with vitamin E.

Studies, doses and limits

What the trials found

da Costa Hime 2021: 96 postmenopausal women with high blood pressure took 1,000 mg of borage oil rich in GLA plus vitamin E, or vitamin E alone, for 6 months. Systolic and diastolic pressure and waist-hip ratio were significantly lower with the borage oil.

Results

Possible benefit, not repeated.

Effect sizes as reported

Significant (P < 0.01) fall in blood pressure and waist-hip ratio; numbers not given in the abstract.

Why this rating

One trial; no second trial; the comparison was vitamin E alone.

Form and dose studied

Borage oil 1,000 mg with vitamin E.

Who was studied

Postmenopausal women with high blood pressure.

Limits

Only one trial; the abstract gives no numbers.

Why researchers looked

Menopause is linked to higher blood pressure and weight around the waist.

Proposed mechanism Not tested

No mechanism was tested.

A proposed mechanism does not show that the effect happens in people.

Do not use it instead of blood pressure medicine. Ask a doctor.

²⁰

Starting labour and softening the cervix

Mixed findings

Evening primrose oil has been tried by mouth or in the vagina near the end of pregnancy. Results are inconsistent and a 2022 review does not recommend it.

3 studiesOral or vaginal capsules, used under clinical care.

Studies, doses and limits

What the trials found

Hutcherson 2022 reviewed 11 studies: adverse events were generally mild (higher blood pressure, lower heart rate, pain, bleeding, nausea and vomiting), risk of bias was important, and the authors do not recommend use. Ariana 2024 (96 women, vaginal 1,000 mg capsule): Bishop score 5.83 versus 5.19 (p = 0.002) and less oxytocin need (10.4% versus 31.3%). NCCIH says results are inconsistent.

Results

Inconsistent; one recent trial positive, the review not recommending it.

Effect sizes as reported

Bishop score 5.83 vs 5.19 (p = 0.002); oxytocin 10.4% vs 31.3% (p = 0.012).

Why this rating

A positive recent trial against a review that found important bias and does not recommend it; NCCIH says long-term safety is not established.

Form and dose studied

Oral or vaginal capsules, used under clinical care.

Who was studied

Women at the end of pregnancy.

Limits

Single-hospital trials; risk of bias; long-term safety not established.

Why researchers looked

People look for natural ways to start labour.

Traditional use

NCCIH says evening primrose oil has been used orally or vaginally to try to start labour.

Proposed mechanism Author hypothesis

The idea is that GLA raises prostaglandins that soften the cervix. This has not been confirmed.

A proposed mechanism does not show that the effect happens in people.

Only under midwife or doctor care. Do not use it to start labour on your own.

^{8 3 22}

Inflammatory conditions overall

Not enough evidence

A 2024 review of evening primrose oil trials in many inflammatory conditions found mixed results and no basis for strong recommendations.

1 studiesEvening primrose oil.

Studies, doses and limits

What the trials found

Sharifi 2024 reviewed randomised trials: mixed in rheumatoid arthritis, some results in diabetes, eczema, hot flashes and breast pain, no shown effect for hand dermatitis, PMS, acne, psoriasis, Sjogren's syndrome and others. The authors say the literature is highly heterogeneous and fails to give strong recommendations.

Results

No firm conclusion.

Effect sizes as reported

No pooled effect size.

Why this rating

The review itself says the trials are too varied. Its acne finding disagrees with the one borage trial above.

Form and dose studied

Evening primrose oil.

Who was studied

Varied conditions.

Limits

Very varied trials.

Why researchers looked

GLA is an omega-6 fat linked to inflammation signalling, so reviewers asked whether it helps inflammatory diseases in general.

Proposed mechanism Not tested

Not tested in the review.

A proposed mechanism does not show that the effect happens in people.

See the Safety tab.

¹³

Connections to the rest of health

How Evening primrose, borage and GLA oils connects to the rest of our health knowledge graph. Every link says what kind of connection it is. A safety link (for example to the liver) is a warning, not a benefit. A study that merely mentions a topic never creates a benefit link.

Explore every connection: goals, body systems, organs, symptoms, genes

Kind of connection Connected to Search

A. Wellness goals

Connected to	Evidence status	Context	Studies
Balanced Nutrition	High certainty	A source of GLA, an omega-6 fat: Evening primrose oil and borage oil are seed oils that contain gamma-linolenic acid (GLA), an omega-6 fat. They are not omega-3 oils like fish oil. Borage oil is richer in GLA (about 25%) than evening primrose oil (about 10%), according to one cancer-centre source.	^{22 21}
Healthy Skin	Evidence against	Eczema (atopic dermatitis): Both oils were widely thought to help eczema because of their GLA. A large review and a good-sized borage trial found they work no better than placebo.	^{4 14 22}
Joint Support	Low certainty	Rheumatoid arthritis pain and joint symptoms: Some older trials of GLA oils found less joint pain and swelling in rheumatoid arthritis. Reviews call the evidence limited, and the amounts in the trials were far higher than in usual products.	^{5 12 19 22}
Womens Wellness	Evidence against	Breast pain (mastalgia): Reviews found evening primrose oil no better than placebo or standard treatments for breast pain. Premenstrual syndrome (PMS): Two reviews found no benefit of evening primrose oil for PMS. Other options, such as calcium, had better evidence.	^{1 22 17 6}
Menopause Support	Mixed findings	Menopause hot flashes: Reviews disagree. A 2024 review found milder hot flashes under 6 months but no change in how many or how long. A 2025 review found no significant change in number but shorter hot flashes. Both call the evidence limited.	^{15 11 22}
Blood Sugar	Low certainty	Diabetic nerve damage (neuropathy): A 1993 trial found GLA slowed nerve changes in mild diabetic neuropathy. Newer trials are small, short or had no placebo-only group. Evidence is limited.	^{10 18 7}
Healthy Skin	Very low certainty	Acne: One small 10-week trial reported fewer acne spots with borage oil (and with fish oil). It is one study, and another review lists acne among uses without shown effect for evening primrose oil.	^{9 13}
Blood Pressure Support	Very low certainty	Blood pressure and body fat after menopause: One 6-month Brazilian trial reported lower blood pressure and waist-hip ratio with borage oil. It is a single trial and the comparison group also got vitamin E.	²⁰
Pregnancy Support	Mixed findings	Starting labour and softening the cervix: Evening primrose oil has been tried by mouth or in the vagina near the end of pregnancy. Results are inconsistent and a 2022 review does not recommend it.	^{8 3 22}
Inflammation Balance	Not enough evidence	Inflammatory conditions overall: A 2024 review of evening primrose oil trials in many inflammatory conditions found mixed results and no basis for strong recommendations.	¹³

B. Body systems

Connected to	Kind of connection	Evidence status	Context	Studies
Whole Body	Biological association	High certainty	Studied for: A source of GLA, an omega-6 fat	^{22 21}
Integumentary System	Biological association	Evidence against	Studied for: Eczema (atopic dermatitis) Studied for: Acne	^{4 14 22 9 13}
Musculoskeletal System	Biological association	Low certainty	Studied for: Rheumatoid arthritis pain and joint symptoms	^{5 12 19 22}
Reproductive System	Biological association	Evidence against	Studied for: Breast pain (mastalgia) Studied for: Premenstrual syndrome (PMS)	^{1 22 17 6 15 11 8 3}
Nervous System	Biological association	Low certainty	Studied for: Diabetic nerve damage (neuropathy)	^{10 18 7}
Endocrine System	Biological association	Low certainty	Studied for: Diabetic nerve damage (neuropathy)	^{10 18 7}
Cardiovascular System	Biological association	Very low certainty	Studied for: Blood pressure and body fat after menopause	²⁰
Immune System	Biological association	Not enough evidence	Studied for: Inflammatory conditions overall	¹³

E. Health conditions

Connected to	Kind of connection	Evidence status	Context	Studies
Eczema		Evidence against	Cochrane review and a BMJ trial found no benefit over placebo. Preparation or compound: Evening primrose oil, borage oil	^{4 14}

I. Biomarkers

Connected to	Kind of connection	Evidence status	Context	Studies
Eczema sign score (SASSAD)	Biological association	Evidence against	Measured in trials: no change (placebo did as well). A lab change is not the same as a health benefit.	¹⁴
Tender and swollen joint counts in rheumatoid arthritis	Biological association	Low certainty	Measured in trials: lower (small older trial). A lab change is not the same as a health benefit.	¹²
Hot flash frequency, severity and duration	Biological association	Mixed findings	Measured in trials: mixed. A lab change is not the same as a health benefit.	^{15 11}
Breast pain relief	Biological association	Evidence against	Measured in trials: no difference from placebo. A lab change is not the same as a health benefit.	¹
Nerve conduction and nerve function tests	Biological association	Low certainty	Measured in trials: better than placebo (1993 trial). A lab change is not the same as a health benefit.	¹⁰
Nerve pain score (0 to 10)	Biological association	Low certainty	Measured in trials: lower. A lab change is not the same as a health benefit.	^{18 7}
Acne lesion count	Biological association	Very low certainty	Measured in trials: lower (one small trial). A lab change is not the same as a health benefit.	⁹
Blood pressure (systolic and diastolic)	Biological association	Very low certainty	Measured in trials: lower (one trial). A lab change is not the same as a health benefit.	²⁰
Bishop score (cervix readiness)	Biological association	Low certainty	Measured in trials: higher (one trial). A lab change is not the same as a health benefit.	^{3 8}

J. Genes, receptors and enzymes

Connected to	Kind of connection	Evidence status	Context	Studies
Fatty acid desaturase region (rs174537)	Preliminary mechanism	Human	May change how well people raise GLA and DGLA from borage oil.	²¹

K. Biological pathways

Connected to	Kind of connection	Evidence status	Context	Studies
Omega-6 fatty acids (linoleic acid, DGLA, arachidonic acid)	Preliminary mechanism	Human	GLA sits inside the omega-6 pathway.	²¹

L. Active compounds

Connected to	Kind of connection	Evidence status	Context	Studies
Gamma-linolenic acid (GLA)	Biological association	Human	The body can convert GLA to DGLA, a building block for inflammation-signalling chemicals. Preparation or compound: Seed oil	^{21 22}
Linoleic acid	Biological association	Human	The parent omega-6 fat from which the body makes GLA; present in both oils (Memorial Sloan Kettering for borage). Preparation or compound: Seed oil	²¹
Dihomo-gamma-linolenic acid (DGLA)	Biological association	Lab	Described as able to block the changing of arachidonic acid into leukotrienes and other prostaglandins (Memorial Sloan Kettering). Preparation or compound: Made in the body from GLA	²¹
Pyrrolizidine alkaloids (amabiline, supinine, lycopsamine, intermedine and others)	Biological association	Human	Liver-toxic in higher amounts (Memorial Sloan Kettering). Preparation or compound: Borage plant; should be absent from certified oil	^{21 16}

Each connection is stored with the ingredient, the connected record, the kind of connection, the evidence status, the supporting studies, the preparation or compound involved, and a review date (last reviewed October 26, 2026).

Evidence at a glance: what changed in 1 lab markers

Tap a number to show only those markers. Counts are markers, not people.

Other1

The evidence

The research centre for Evening primrose, borage and GLA oils. Every record here was checked against PubMed or the publisher's page; we never list a study we have not verified.

Evidence by outcome

A source of GLA, an omega-6 fat 2 studies High certainty Eczema (atopic dermatitis) 3 studies Evidence against Rheumatoid arthritis pain and joint symptoms 4 studies Low certainty Breast pain (mastalgia) 2 studies Evidence against Premenstrual syndrome (PMS) 3 studies Evidence against Menopause hot flashes 3 studies Mixed findings Diabetic nerve damage (neuropathy) 3 studies Low certainty Acne 2 studies Very low certainty Blood pressure and body fat after menopause 1 study Very low certainty Starting labour and softening the cervix 3 studies Mixed findings Inflammatory conditions overall 1 study Not enough evidence

Bars show how many studies we found for each outcome, not how well it works. People are added up across trials only (reviews are not added, to avoid double counting).

How we rate evidence

High certainty

Several well-run trials or reviews agree; further research is unlikely to change the picture much.

Moderate certainty

Good trials point the same way, but some doubt remains.

Low certainty

Small, short or inconsistent trials. The finding could change with better research.

Very low certainty

Very little or very weak human data. Treat as a possibility only.

Mixed findings

Trials or reviews disagree with each other.

Not enough evidence

Not enough human research to say either way.

Evidence against

Good research found no benefit, or found harm.

We take the reviewers' own risk-of-bias and GRADE statements where they exist, and otherwise judge from study size, design, consistency, directness and whether a product matches what is sold. Many publications do not make evidence high. Method note: We read the NCCIH page on evening primrose oil and the Memorial Sloan Kettering page on borage in full, and read the PubMed abstracts for the trials and reviews cited. Only abstracts were read for studies. The NIH Office of Dietary Supplements and LactMed pages could not be read and are marked unread.

Study library: every study we checked 22

Design Research type Year from Search

Study	Design	People	Product, dose, length	Result
Ahmad Adni 2021 A Systematic Review and Meta-Analysis of the Efficacy of Evening Primrose Oil for Mastalgia Treatment. International Journal of Environmental Research and Public Health · PMID 34200727 · DOI	Systematic review meta analysis	1752 13 randomised trials of 1,752 women with breast pain (mastalgia)	Evening primrose oil Seed oil Varied; not given in the abstract Varied · vs Placebo, topical NSAIDs, danazol or vitamin E	Evening primrose oil was no different from placebo, topical NSAIDs, danazol or vitamin E in pain relief. It did not increase side effects such as nausea, bloating, headache or altered taste compared with placebo or the other treatments. No difference in the number achieving pain relief versus placebo or other treatments (Not given in the abstract) Methods, limits and funding Outcomes: Pain relief; adverse events Limitations: Trial quality and sizes are not given in the abstract. Funding and conflicts: The authors declare no conflict of interest. Read: abstract
Al-Khamees 2011 Status epilepticus associated with borage oil ingestion. Journal of Medical Toxicology · PMID 21387119 · DOI	Case report	1 One person who took borage oil for one week (Georgia Poison Center report)	Borage oil Seed oil Not given in the abstract One week	A case of status epilepticus, a prolonged dangerous seizure, was reported in a person who took borage oil for a week. One case cannot show the oil caused it. One case (Not applicable) Methods, limits and funding Outcomes: Seizure (status epilepticus) Limitations: Single case report; cause not established. Funding and conflicts: Not stated in the abstract. Read: abstract
Ariana 2024 The Use of Evening Primrose Oil for Cervical Ripening in Low-Risk Women with Term Pregnancy: A Randomized Double-Blinded Controlled Trial. Complementary Medicine Research · PMID 38377980 · DOI	Randomised controlled trial	96 96 low-risk women at term pregnancy in Tehran (48 per group)	Evening primrose oil, placed in the vagina Seed oil 1,000 mg capsule a day · vs Vaginal placebo capsule	Bishop score was higher after the oil than placebo, and fewer in the oil group needed oxytocin. Caesarean rates did not differ (4 versus 2). The authors say vaginal use could be considered safe and efficient in this group. This was a vaginal use under clinical supervision, not a supplement for home use. Bishop score 5.83 versus 5.19 (p = 0.002); oxytocin needed 10.4% versus 31.3% (p = 0.012) (Not given in the abstract) Methods, limits and funding Outcomes: Bishop score (primary); labour duration; induction methods Limitations: Single trial at one hospital. The abstract's amniotomy figures read inconsistently, so they are not reported here. The authors of the 2022 review did not recommend this use. Funding and conflicts: Not stated in the abstract. Read: abstract
Bamford 2013 Oral evening primrose oil and borage oil for eczema. Cochrane Database of Systematic Reviews · PMID 23633319 · DOI	Systematic review meta analysis	1596 27 trials in people with atopic eczema (19 of evening primrose oil, 8 of borage oil); searches to August 2012	Oral evening primrose oil or borage oil Seed oil (capsules) Varied by trial; not given in the abstract Short-term trials; length not given in the abstract · vs Placebo	Evening primrose oil did not significantly improve eczema compared with placebo, by patient or doctor rating. Borage oil also failed to improve global symptoms compared with placebo (no pooling possible). The authors say oral borage oil and evening primrose oil are not effective for eczema, and that adverse effects were mild, mostly gastrointestinal, and similar to placebo. Evening primrose oil, patient rating: mean difference -2.22 (7 trials, 176 people). Doctor rating: -3.26 (8 trials, 289 people). (95% CI -10.48 to 6.04 (patients); -6.96 to 0.45 (doctors)) Methods, limits and funding Outcomes: Global eczema symptoms rated by patients and by doctors (100-point scale) Limitations: Short-term trials only: long-term harm was not examined. 67% of trials were judged low risk of bias for random sequence generation but only 37% for other biases. Funding and conflicts: Authors' conflict statement: one author's own research was funded by a grant repaid by Efamol Pharmaceutical, which supplied medicine, placebo and blood tests for a trial included in the review (he did not extract that trial's data). Read: abstract
Cameron 2011 Herbal therapy for treating rheumatoid arthritis. Cochrane Database of Systematic Reviews · PMID 21328257 · DOI	Systematic review meta analysis	22 trials of herbal treatments in rheumatoid arthritis; seven were of GLA oils	GLA from evening primrose oil, borage seed oil or blackcurrant seed oil Seed oil Varied; not given in the abstract Varied · vs Placebo	Seven trials suggested less pain and less disability with GLA oils. Adverse events were more common with GLA (20% versus 3% on placebo) but the difference was not statistically significant. The authors call the evidence 'moderate' that these oils give some benefit, and warn many herbal trials have design flaws and poor reporting. Pain: mean difference -32.83 points (100-point scale). Disability: -15.75%. Adverse events: relative risk 4.24 (Pain 95% CI -56.25 to -9.42; disability -27.06 to -4.44; adverse events 0.78 to 22.99) Methods, limits and funding Outcomes: Pain on a 100-point scale; disability; adverse events Limitations: The pooled trials mixed three different oils. The adverse-event interval is wide and includes no difference. Funding and conflicts: The authors report no known conflict of interest. Read: abstract
Dante 2011 Herbal treatments for alleviating premenstrual symptoms: a systematic review. Journal of Psychosomatic Obstetrics and Gynaecology · PMID 21171936 · DOI	Systematic review	10 randomised trials of herbs in PMS or PMDD (of 17 eligible)	Several herbs, including evening primrose oil Mixed Varied Varied · vs Placebo	Chasteberry was the best studied and was reported to ease PMS better than placebo. Neither evening primrose oil nor St John's wort showed an effect different from placebo. No major health risks were seen, but too few people were tested to be sure about safety. No pooled effect size (trials too different to combine) (Not applicable) Methods, limits and funding Outcomes: PMS symptom relief Limitations: Evening primrose oil was one of many herbs; the abstract gives no trial count for it. Funding and conflicts: Not stated in the abstract. Read: abstract
Gholami 2025 Effects of evening primrose oil on treating painful diabetic neuropathy: a randomized, double-blind, clinical trial. Journal of Complementary and Integrative Medicine · PMID 40418820 · DOI	Randomised controlled trial	66 66 people with painful diabetic neuropathy in Iran	Evening primrose oil soft gels Seed oil 1,000 mg every 12 hours (group A) or 1,000 mg a day (group B) 4 weeks · vs Placebo capsules (half daily, half every 12 hours)	Both oil groups had lower pain scores than placebo; the twice-daily group improved most (pain score 5.96 before, 4.63 after). The authors call it a possible alternative therapy and ask for more research. Twice-daily versus once-daily: pain difference -0.52 (p = 0.044) (Not given in the abstract) Methods, limits and funding Outcomes: Pain on a 10-point visual analogue scale; neuropathy symptom score; McGill pain score Limitations: Small (21 to 24 per group), only 4 weeks, self-reported pain, unusual placebo arrangement. The abstract does not name a trial registration. Funding and conflicts: Not stated in the abstract. Read: abstract
Hutcherson 2022 Systematic Review of Evening Primrose (Oenothera biennis) Preparations for the Facilitation of Parturition. Pharmacy (Basel) · PMID 36548328 · DOI	Systematic review	11 studies in people near the end of pregnancy (7 randomised placebo-controlled trials, plus other designs)	Evening primrose preparations (oral and vaginal) Seed oil Varied Varied · vs Placebo or no treatment	Adverse events were generally mild: higher blood pressure, lower heart rate, pain, bleeding, nausea and vomiting. Important risks of bias exist across the studies. The authors do not recommend evening primrose for starting labour and call for more research. No pooled effect size in the abstract (Not applicable) Methods, limits and funding Outcomes: Bishop score (cervix readiness), duration of labour, adverse events Limitations: Review was not registered or funded; risk of bias across the literature. Funding and conflicts: The authors deny conflicts of interest; the review was neither registered nor funded. Read: abstract
Jung 2014 Effect of dietary supplementation with omega-3 fatty acid and gamma-linolenic acid on acne vulgaris: a randomised, double-blind, controlled trial. Acta Dermato-Venereologica · PMID 24553997 · DOI	Randomised controlled trial	45 45 people with mild to moderate acne in Korea	Borage oil containing 400 mg GLA (one arm); omega-3 fish oil with 2,000 mg EPA plus DHA (another arm) Borage seed oil 400 mg GLA a day 10 weeks · vs Control group (type not described in the abstract)	Inflammatory and non-inflammatory lesions fell significantly after 10 weeks in the omega-3 and GLA groups. Patient ratings agreed. No severe side effects were reported. The authors suggest these could be adjuvant treatments. Not given as numbers in the abstract (Not given in the abstract) Methods, limits and funding Outcomes: Inflammatory and non-inflammatory acne lesion counts; skin biopsy staining Limitations: Only 45 people over three groups; the control is not described as a placebo in the abstract; one short trial. A 2024 review lists acne among uses where evening primrose oil did not show effectiveness (a different oil). Funding and conflicts: Not stated in the abstract. Read: abstract
Keen 1993 Treatment of diabetic neuropathy with gamma-linolenic acid. The gamma-Linolenic Acid Multicenter Trial Group. Diabetes Care · PMID 8380765 · DOI	Randomised controlled trial	111 111 people with mild diabetic neuropathy at seven centres	Gamma-linolenic acid (source oil not stated in the abstract) 480 mg of GLA a day 1 year · vs Placebo	GLA gave a more favourable change than placebo on all 16 measures, statistically significant for 13. It worked better in people whose diabetes was better controlled. 13 of 16 measures significantly better than placebo (Not given in the abstract) Methods, limits and funding Outcomes: Nerve conduction, thresholds, sensation, reflexes and muscle strength (16 measures) Limitations: Nearly 30 years old; mild neuropathy; the abstract does not say which oil supplied the GLA. Not repeated in the trials we read. Funding and conflicts: Not stated in the abstract. Read: abstract
Larki 2025 The Effect of Evening Primrose Oil on Menopausal Symptoms Management: A Systematic Review and Meta-Analysis. Journal of Caring Sciences · PMID 41883983 · DOI	Systematic review meta analysis	450 Six randomised trials in menopausal women (450 women in the meta-analysis)	Evening primrose oil Seed oil Not given in the abstract Not given in the abstract · vs Control or no supplement	Hot flashes per day fell by 2.13 more with the oil than control, but this was not statistically significant. Duration of hot flashes fell significantly. Intensity fell by 0.19, not significant. The authors rate the evidence moderate to low and say more rigorous research is needed. Mean difference in daily hot flashes -2.13 (not significant); intensity -0.19 (not significant) (Not given in the abstract) Methods, limits and funding Outcomes: Hot flashes per day, duration and intensity Limitations: Only six trials; evidence graded moderate to low. This review disagrees with the 2024 review on duration. Funding and conflicts: Not stated in the abstract. Read: abstract
Leventhal 1993 Treatment of rheumatoid arthritis with gammalinolenic acid. Annals of Internal Medicine · PMID 8214997 · DOI	Randomised controlled trial	37 37 people with rheumatoid arthritis and active joint inflammation at a US university clinic	Gammalinolenic acid in borage seed oil Seed oil 1.4 g of GLA a day 24 weeks · vs Cottonseed oil	GLA reduced signs and symptoms. Tender joint count fell 36%, swollen joint count 28%. The placebo group showed no improvement or got worse. No one dropped out because of side effects. The authors note this was a much higher amount than is usually taken and that GLA should not be viewed as therapy for any disease. Tender joints -36%; tender joint score -45%; swollen joints -28%; swollen joint score -41% (Not given in the abstract) Methods, limits and funding Outcomes: Doctor and patient global ratings, tender and swollen joints, morning stiffness, grip strength Limitations: Small trial. Amount of GLA was far higher than in usual products. Nearly 30 years old. Funding and conflicts: Listed in PubMed as supported by a US government research grant (PHS); no company funding is stated in the abstract. Read: abstract
Sharifi 2024 The effect of Oenothera biennis (Evening primrose) oil on inflammatory diseases: a systematic review of clinical trials. BMC Complementary Medicine and Therapies · PMID 38360611 · DOI	Systematic review	Randomised trials of evening primrose oil in people with inflammatory conditions	Evening primrose oil Seed oil Varied Varied · vs Placebo or other treatments	Results were mixed in rheumatoid arthritis. Some results were reported for diabetes, eczema, hot flashes and breast pain. No effectiveness was shown for hand dermatitis, PMS, acne, psoriasis, Sjogren's syndrome and several others. The authors say the literature is highly heterogeneous and fails to give strong recommendations. No pooled effect size (Not applicable) Methods, limits and funding Outcomes: Symptoms and inflammatory markers Limitations: Very varied trials, so no firm conclusion. Funding and conflicts: The authors declare no competing interests. Read: abstract
Takwale 2003 Efficacy and tolerability of borage oil in adults and children with atopic eczema: randomised, double blind, placebo controlled, parallel group trial. BMJ · PMID 14670885 · DOI	Randomised controlled trial	151 151 adults and children with atopic eczema recruited at one English hospital; 140 evaluable (69 children)	Borage oil capsules (high in GLA) Seed oil Adults: 920 mg GLA a day; children: half the capsules 12 weeks · vs Placebo capsules	No benefit over placebo. The authors conclude GLA is not beneficial in atopic dermatitis. The treatments were well tolerated. Mean SASSAD score fell from 30 to 27 on borage oil and from 28 to 23 on placebo; difference 1.4 points in favour of placebo (P = 0.45) (95% CI -2.2 to 5.0) Methods, limits and funding Outcomes: Eczema sign score (SASSAD) at 12 weeks; symptoms; steroid cream use Limitations: One centre; 11 of 151 did not return. Funding and conflicts: Not stated in the abstract. Read: abstract
Thevi 2024 Evening Primrose Oil for Menopause Hot Flashes: Systematic Review and Meta-Analysis. Journal of Menopausal Medicine · PMID 39829189 · DOI	Systematic review meta analysis	Menopausal women with hot flashes in randomised or controlled trials; number of trials and women not given in the abstract	Evening primrose oil Seed oil Not given in the abstract Under 6 months in the trials that showed lower severity · vs Placebo, other treatments (black cohosh)	Severity was lower with evening primrose oil than placebo when used for less than 6 months. Frequency and duration did not differ from placebo. Against black cohosh, severity was similar at 4 weeks but worse at 8 weeks with evening primrose oil. Side effects were mild nausea and headache. The authors say the evidence is insufficient for firm conclusions. Not given as a number in the abstract (Not given in the abstract) Methods, limits and funding Outcomes: Hot flash severity, frequency and duration Limitations: Abstract gives no trial count or effect sizes. The authors call the evidence insufficient. Funding and conflicts: The authors report no conflict of interest. Read: abstract
Vacillotto 2013 A rapid and highly specific method to evaluate the presence of pyrrolizidine alkaloids in Borago officinalis seed oil. Journal of Mass Spectrometry · PMID 24130010 · DOI	Laboratory analysis laboratory	1 One commercially available borage seed oil tested in the laboratory	Borage seed oil Seed oil	The authors say earlier methods suggested these liver-toxic alkaloids are not carried into the oil. In the one sample tested, any alkaloids present were below the method's detection limit of about 200 parts per trillion. They note there is no international regulation of these alkaloids in foods. Below about 200 ppt in the one sample (Not applicable) Methods, limits and funding Outcomes: Presence of pyrrolizidine alkaloids Limitations: One sample only; says nothing about other brands or batches. Funding and conflicts: Not stated in the abstract. Read: abstract
Whelan 2009 Herbs, vitamins and minerals in the treatment of premenstrual syndrome: a systematic review. Canadian Journal of Clinical Pharmacology · PMID 19923637	Systematic review	Randomised trials of herbs, vitamins and minerals for PMS (62 products identified, trial evidence for 10)	Several products, including evening primrose oil Mixed Varied Varied · vs Placebo or recognised therapy	No evidence of benefit was found with evening primrose oil. Only calcium had good-quality evidence. Chasteberry and vitamin B6 may be effective. No pooled effect size (Not applicable) Methods, limits and funding Outcomes: PMS symptom severity Limitations: Trials differed too much to combine. Searches ended in April 2008. Funding and conflicts: Not stated in the abstract. Read: abstract
Won 2020 gamma-Linolenic Acid versus alpha-Lipoic Acid for Treating Painful Diabetic Neuropathy in Adults: A 12-Week, Double-Placebo, Randomized, Noninferiority Trial. Diabetes and Metabolism Journal · PMID 31701699 · DOI	Randomised controlled trial	100 100 adults with type 2 diabetes and painful diabetic nerve damage in Korea; 73 finished	Gamma-linolenic acid 320 mg of GLA a day 12 weeks · vs Alpha-lipoic acid 600 mg a day (an antioxidant, not alpha-linolenic acid); double-dummy placebo	Pain fell in both groups with no difference between them. For pain, GLA met the study's noninferiority margin against alpha-lipoic acid. For total symptom score it did not clearly meet the margin. There was no placebo-only group, so this trial cannot show GLA beats placebo. Pain difference -0.65 between groups; symptom score difference -0.05 (Pain 95% CI -1.526 to 0.213; symptom score -1.211 to 1.101) Methods, limits and funding Outcomes: Pain (visual analogue scale) and total symptom score Limitations: No placebo-alone arm; 27 of 100 did not finish. Funding and conflicts: Supported by a grant from Dalin Biotech Korea Co. Ltd. (industry); the funder had no role in design, analysis or publication, per the paper. Read: abstract
Zurier 1996 gamma-Linolenic acid treatment of rheumatoid arthritis. A randomized, placebo-controlled trial. Arthritis and Rheumatism · PMID 8912502 · DOI	Randomised controlled trial	56 56 people with active rheumatoid arthritis	Gamma-linolenic acid as a free fatty acid derived from plant seed oil (not a whole seed oil) Purified fatty acid in capsules 2.8 g of GLA a day 6 months double-blind, then 6 months open-label · vs Sunflower seed oil	GLA gave statistically significant and clinically relevant reductions in disease activity over placebo at 6 months. 14 of 22 on GLA met the response definition versus 4 of 19 on placebo. Responders 14/22 versus 4/19 (P = 0.015) (Not given in the abstract) Methods, limits and funding Outcomes: Signs and symptoms of disease activity; responders (at least 25% better on 4 measures) Limitations: Small. The amount (2.8 g) is far above usual product amounts, and the form was purified GLA, not evening primrose or borage oil as sold. Funding and conflicts: Listed in PubMed as supported by US government research grants; no company funding is stated in the abstract. Read: abstract
da Costa Hime 2021 Is there a beneficial effect of gamma-linolenic acid supplementation on body fat in postmenopausal hypertensive women? A prospective randomized double-blind placebo-controlled trial. Menopause · PMID 33534427 · DOI	Randomised controlled trial	96 96 postmenopausal women with high blood pressure in Brazil	Borage oil rich in GLA plus vitamin E Seed oil 1,000 mg of borage oil a day 6 months · vs Vitamin E capsules only	Systolic and diastolic blood pressure and waist-to-hip ratio were significantly lower in the borage oil group than the vitamin E-only group. No adverse effect was reported. The authors say long-term benefit still needs study. Significant (P < 0.01) fall in blood pressure and waist-hip ratio; numbers not given in the abstract (Not given in the abstract) Methods, limits and funding Outcomes: Blood pressure and body composition Limitations: A single trial. The comparison was vitamin E alone, not an inactive capsule, and the borage group also got vitamin E. Funding and conflicts: Not stated in the abstract. Read: abstract
s-msk-borage Memorial Sloan Kettering Cancer Center: Borage, Purported Benefits, Side Effects and More (About Herbs; last updated 31 March 2022) · Source	Regulator page n/a			Methods, limits and funding Read: full-text
s-nccih-epo NCCIH: Evening Primrose Oil: Usefulness and Safety (last updated November 2024) · Source	Regulator page n/a			Methods, limits and funding Read: full-text

What we do not know yet

No head-to-head trial compared evening primrose oil with borage oil.
The NIH Office of Dietary Supplements and LactMed pages could not be read, so no official upper limit for GLA is stated.
Only one commercial borage oil was tested for alkaloids in the sources read.
No recent large trial of a usual product for rheumatoid arthritis or nerve damage was found.
Long-term safety beyond a few months is not established.
Food allergy to these oils was not found in the sources read.

How new research is added

New studies are found by a saved PubMed search and placed in a review queue before the page changes.

Lab markers

What changed in blood or saliva tests during trials. A changed number is not the same as feeling or being healthier, and we give no "normal ranges".

Other 9

●

Eczema sign score (SASSAD)

No change (placebo did as well) in trials

A doctor's score of how severe eczema signs are across the skin.

Evidence against

Results and what it means

Why it was measured

To see whether borage oil changes visible eczema.

Statistical vs. clinical meaning

No benefit over placebo.

Safety implication

No safety signal in this trial.

Study	Result	People	Product
¹⁴	Fell from 30 to 27 on borage oil and 28 to 23 on placebo; difference 1.4 points favouring placebo (P = 0.45)	140 adults and children with eczema	Borage oil (920 mg GLA a day in adults) for 12 weeks

¹⁴

●

Tender and swollen joint counts in rheumatoid arthritis

Lower (small older trial) in trials

How many joints hurt on pressure or are swollen.

Low certainty

Results and what it means

Why it was measured

To see whether GLA oils calm joint inflammation.

Statistical vs. clinical meaning

A small 1993 trial using far more GLA than usual products.

Safety implication

No one dropped out for side effects in this trial.

Study	Result	People	Product
¹²	Tender joint count -36%, swollen joint count -28%; placebo group did not improve	37 people with active rheumatoid arthritis	1.4 g GLA a day in borage seed oil for 24 weeks

¹²

↕

Hot flash frequency, severity and duration

Mixed results in trials

How often hot flashes occur, how strong they are and how long they last.

Mixed findings

Results and what it means

Why it was measured

To see whether the oil eases menopause symptoms.

Statistical vs. clinical meaning

The two reviews disagree on duration.

Safety implication

Mild nausea and headache.

Study	Result	People	Product
¹⁵	Severity lower than placebo under 6 months; frequency and duration not different	Menopausal women (number not given in the abstract)	Evening primrose oil
¹¹	Daily hot flashes -2.13 (not significant); duration significantly shorter; intensity -0.19 (not significant)	450 women in 6 trials	Evening primrose oil

^{15 11}

●

Breast pain relief

No difference from placebo in trials

Whether a woman reports less breast pain.

Evidence against

Results and what it means

Why it was measured

To see whether the oil works against breast pain.

Statistical vs. clinical meaning

No benefit shown.

Safety implication

No extra side effects reported.

Study	Result	People	Product
¹	No difference in pain relief versus placebo or other treatments	1,752 women in 13 trials	Evening primrose oil

●

Nerve conduction and nerve function tests

Better than placebo (1993 trial) in trials

Tests of how fast and well nerves carry signals, plus sensation and reflexes.

Low certainty

Results and what it means

Why it was measured

To see whether GLA slows nerve damage in diabetes.

Statistical vs. clinical meaning

One older trial; not repeated against placebo in the trials read.

Safety implication

No safety signal in the abstract.

Study	Result	People	Product
¹⁰	All 16 measures changed more favourably than placebo; 13 significantly	111 people with mild diabetic neuropathy	GLA 480 mg a day for 1 year

¹⁰

●

Nerve pain score (0 to 10)

Lower in trials

A person's own rating of nerve pain.

Low certainty

Results and what it means

Why it was measured

To see whether the oil eases painful neuropathy.

Statistical vs. clinical meaning

Small trials; one had no placebo-only group; one lasted only 4 weeks.

Safety implication

Medicines should not be stopped.

Study	Result	People	Product
¹⁸	Pain fell in both GLA and alpha-lipoic acid groups; difference -0.65, GLA noninferior for pain	100 adults (73 finished)	GLA 320 mg a day for 12 weeks
⁷	Twice-daily group pain 5.96 to 4.63; more effective than once daily (-0.52, p = 0.044)	66 people	Evening primrose oil 1,000 mg once or twice a day for 4 weeks

^{18 7}

●

Acne lesion count

Lower (one small trial) in trials

How many inflamed and non-inflamed spots are on the skin.

Very low certainty

Results and what it means

Why it was measured

To see whether borage oil or fish oil reduces acne.

Statistical vs. clinical meaning

One small trial.

Safety implication

No severe side effects reported.

Study	Result	People	Product
⁹	Inflammatory and non-inflammatory lesions decreased significantly after 10 weeks	45 people with mild to moderate acne	Borage oil with 400 mg GLA

⁹

●

Blood pressure (systolic and diastolic)

Lower (one trial) in trials

The pressure in the arteries when the heart beats and rests.

Very low certainty

Results and what it means

Why it was measured

To see whether borage oil lowers blood pressure.

Statistical vs. clinical meaning

One trial; numbers not given in the abstract.

Safety implication

Do not replace blood pressure medicine.

Study	Result	People	Product
²⁰	Significant fall in systolic and diastolic pressure and waist-hip ratio versus vitamin E alone	96 postmenopausal women with high blood pressure	Borage oil 1,000 mg plus vitamin E for 6 months

²⁰

●

Bishop score (cervix readiness)

Higher (one trial) in trials

A score a midwife or doctor gives for how ready the cervix is for labour.

Low certainty

Results and what it means

Why it was measured

To see whether evening primrose oil ripens the cervix.

Statistical vs. clinical meaning

One trial; the 2022 review does not recommend use.

Safety implication

Only under clinical care.

Study	Result	People	Product
³	5.83 with the oil versus 5.19 with placebo (p = 0.002)	96 low-risk women at term	Vaginal evening primrose oil 1,000 mg a day

^{3 8}

Safety

What studies and official sources say about side effects, medicines and who should check first. Each point shows what kind of evidence it comes from.

Main points to know 4

Borage oil should be certified free of liver-toxic alkaloids. Memorial Sloan Kettering says borage contains small amounts of unsaturated pyrrolizidine alkaloids (UPAs) that can damage the liver, and that the risk grows with length of use and total amount. It advises using borage oil certified free of UPAs and says people with liver problems should avoid borage. Its page says 1 to 2 g of borage seed oil a day could give a UPA intake approaching 10 micrograms if the oil were not cleaned, while the German Federal Health Agency set a limit of 1 microgram of UPAs a day. In the one commercial borage seed oil tested in a 2013 laboratory paper, alkaloids were below about 200 parts per trillion. Cancer centre guidance and one laboratory analysis ^{21 16}
Borage should not be used in pregnancy or breastfeeding. Memorial Sloan Kettering says borage should not be used in pregnancy or breastfeeding, because it may have toxic effects on the unborn baby or cause early labour (it also cites an infant blood-oxygen problem tied to eating borage as food). For evening primrose oil, NCCIH says it may be safe in pregnancy and breastfeeding but the evidence is not conclusive. A 2022 review does not recommend it for starting labour. Ask a midwife or doctor. Guidance and systematic review ^{21 22 8}
Possible extra bleeding, especially with blood thinners. The Cochrane eczema review cites one study suggesting evening primrose oil may increase bleeding in people taking warfarin (Coumadin). Memorial Sloan Kettering says that in a small study of GLA from evening primrose oil over several months, 9 of 12 patients had a significant increase in bleeding time. This comes from small studies; it is a reason to ask a pharmacist, not a proven bleeding risk at usual amounts. Small study cited by a review and a cancer centre page ^{4 21}
A case of a prolonged seizure after borage oil. A poison-centre case report describes status epilepticus (a prolonged dangerous seizure) in a person who took borage oil for one week. One report cannot show the oil caused it, but Memorial Sloan Kettering lists it among its adverse-reaction reports. Case report ^{2 21}

Side effects 5

Effect	How often	Severity and recovery	Evidence
Stomach pain, nausea, diarrhoea Mostly gut symptoms.	NCCIH calls these the most common side effects and says evening primrose oil is generally well tolerated. In eczema trials, side effects were mild and similar to placebo.	Mild Not stated in the sources read.	Regulator and systematic review ^{22 4}
Headache, belching, loose stools, abdominal pain Borage oil.	Memorial Sloan Kettering lists these as occasional with borage oil.	Mild Not stated.	Cancer centre guidance ²¹
More side effects in rheumatoid arthritis trials Wide uncertainty.	In seven trials of GLA oils, adverse events were 20% with GLA versus 3% with placebo; the difference was not statistically significant (relative risk 4.24, 95% CI 0.78 to 22.99).	Mostly mild in the abstract Not stated.	Systematic review ⁵
Mild nausea and headache in menopause trials Evening primrose oil.	Reported in the 2024 review; no numbers given.	Mild Not stated.	Systematic review ¹⁵
Higher blood pressure, lower heart rate, pain, bleeding, nausea and vomiting when used for labour Used near the end of pregnancy; only under clinical care.	Generally mild according to the 2022 review; no frequency in the abstract.	Generally mild Not stated.	Systematic review ⁸

Liver

Borage seed oil can carry liver-toxic pyrrolizidine alkaloids if the oil is not cleaned of them; Memorial Sloan Kettering says hepatic damage risk rises with length of exposure and total amount, and that people with liver problems should avoid borage. No source we read reported liver injury from evening primrose oil. The liver-injury database LiverTox was not opened. ^{21 16}

How often. No frequency was found.

Monitoring. No agency monitoring advice was found. Ask a doctor about blood tests if you have liver disease.

This is a safety connection. It is not evidence that Evening primrose, borage and GLA oils supports liver health.

Medicines and supplements 5

With	Why it matters	Importance	Evidence	What to do
Warfarin (Coumadin) and other blood thinners drug	Possible longer bleeding time with GLA from evening primrose oil (small study); borage oil has about two and a half times the GLA.	The Cochrane eczema review cites a study that evening primrose oil may increase bleeding in people on warfarin. Memorial Sloan Kettering extends the caution to borage oil.	Small study cited by review Low certainty ^{4 21}	Ask the prescriber or a pharmacist before combining.
Medicines or supplements that can harm the liver (for example anabolic steroids, ketoconazole) drug	Borage's alkaloids and these medicines can each stress the liver.	Memorial Sloan Kettering lists this as a theoretical concern with borage because of its alkaloids.	Theoretical Very low certainty ²¹	Ask a pharmacist.
NSAID painkillers (such as ibuprofen) drug	NSAIDs block the making of prostaglandins, which is part of how GLA is thought to act.	Memorial Sloan Kettering says that, in theory, using both would lower the effect of borage oil. No human study was read.	Theoretical Very low certainty ²¹	Ask a pharmacist.
Drugs for epilepsy or anything that lowers the seizure threshold drug	Not known.	Only a single case report of seizure with borage oil was read; no interaction study was found.	Case report Very low certainty ²	Ask a doctor if you have epilepsy.
General: any medicine you take drug	Not described.	NCCIH says to talk with a health care provider before using evening primrose oil or other herbal products if you take any medicine, because some herbs and medicines interact in harmful ways.	Regulator High certainty ²²	Ask a pharmacist.

Who should check first 7

Situation	Advice	Evidence
Pregnancy	Borage: Memorial Sloan Kettering says do not use it, because of possible toxic effects on the baby and early labour. Evening primrose oil: NCCIH says it may be safe but evidence is not conclusive; a 2022 review does not recommend it for starting labour. Ask a midwife or doctor.	Guidance and systematic review ^{21 22 8}
Breastfeeding	Evening primrose oil raises the GLA level in breast milk without a link to harm in the infant (NCCIH), but safety is not conclusive. Memorial Sloan Kettering advises against borage during breastfeeding. Ask a doctor or midwife.	Authoritative guidance ^{22 21}
Children	NCCIH says less is known about the safety of evening primrose oil in children. Borage oil: no child advice found other than the pregnancy and liver cautions. Eczema trials included children for 12 weeks without added side effects, but the oils did not help eczema. Ask a doctor.	Guidance and trial ^{22 14}
Liver disease	Memorial Sloan Kettering says people with liver problems should avoid borage. Ask a doctor.	Cancer centre guidance ²¹
Taking blood thinners, or a bleeding disorder	Possible longer bleeding time; ask a pharmacist or prescriber. No source read gave advice for bleeding disorders.	Small study and guidance ^{4 21}
Epilepsy or a seizure history	A single case report links borage oil to a prolonged seizure. Ask a doctor. No evidence was found for evening primrose oil.	Case report ²
Surgery	No source read gave surgery advice. Tell the surgical team about every supplement you take; this is general good practice, not a finding from these sources.	Not established

Overdose, product quality and regulators

Summary. The main toxic concern is not GLA itself but the pyrrolizidine alkaloids that borage plants contain. Borage oil sold for GLA should be certified free of them. Evening primrose oil has no alkaloid concern in the sources read.

Animal. Not reviewed.

High dose or long term signals. The Cochrane eczema review's trials were short. It mentions a case report of possible inflammation, thrombosis and immune suppression after more than a year of evening primrose oil, and says long-term effects are not known. The rheumatoid arthritis trials used amounts well above usual products and report no drop-outs for side effects in the 1993 borage trial.

Overdose response. No source read described a large single swallow of these oils. If someone has swallowed a large amount or feels very unwell, call poison control or emergency services.

Genotoxicity. Not researched.

Toxic or hazardous parts. Borage leaves and flowers contain the alkaloids too and are not the same as the refined oil. Memorial Sloan Kettering also describes one near-fatal case where borage was confused with foxglove, and infant blood-oxygen problems tied to borage purée eaten as food (high in nitrates). Those concern the plant as food, not the oil.

Quality for borage oil depends on alkaloid-free certification. A 2013 laboratory paper tested one commercial borage seed oil and found alkaloids below the method's detection limit of about 200 parts per trillion. The same paper notes there is no international regulation of these alkaloids in foods. Label accuracy, oxidation and heavy-metal testing were not found in the sources read.

Pyrrolizidine alkaloids in borage seed oil. One commercial oil: alkaloids below about 200 ppt. Memorial Sloan Kettering says borage oil products should be certified free of unsaturated alkaloids, meeting no more than 0.5 to 1 microgram per gram (as stated on its page). ^{16 21}

GLA content differs between products. NCCIH and Memorial Sloan Kettering describe evening primrose oil and borage oil as different oils with different GLA shares (about 10% versus about 25%); product labels vary. ^{21 22}

Body	Action	Date
NCCIH (US National Institutes of Health) (United States)	Not enough evidence to support evening primrose oil for any health condition; not shown to help atopic dermatitis; probably no better than placebo for breast pain; inconsistent for starting labour; insufficient for rheumatoid arthritis, PMS and menopause. Probably safe for most adults by mouth; less is known for children; may be safe in pregnancy and breastfeeding but not conclusive. Ask a health care provider about medicines. source	2024-11
Memorial Sloan Kettering Cancer Center (About Herbs: Borage) (United States)	Borage contains hepatotoxic unsaturated pyrrolizidine alkaloids; use oil certified free of them; avoid with liver problems, pregnancy and breastfeeding; interactions listed. This is a hospital patient-education page, not a government regulator. source	2022-03-31

When to get medical help

A seizure, especially one that does not stop: call emergency services.
Yellow skin or eyes, dark urine, severe belly pain or unusual tiredness (possible liver injury, which borage alkaloids can cause): see a doctor promptly.
Unusual bruising or bleeding, or black stools, if you take blood thinners: contact your prescriber.
Wheezing, swelling of the lips or face, hives or trouble breathing after use (possible allergy): get emergency help.
Labour contractions, fluid leaking or bleeding in pregnancy: contact a midwife or doctor at once.
Someone has swallowed a large amount: call poison control or emergency services.

Stop using the product and contact a clinician or emergency service. In the US, Poison Control is 1-800-222-1222.

General information only, not medical advice. Ask a clinician or pharmacist before use, especially with medicines, in pregnancy or with a health condition. See the Natural Remedy Safety guide.

Frequently asked questions

What are evening primrose oil, borage oil and GLA?

Evening primrose oil and borage oil are oils pressed from seeds. Both contain gamma-linolenic acid (GLA), an omega-6 fat. GLA is the part most studied, and some products are sold by their GLA content.

^{22 21}

Are these oils omega-3?

No. NCCIH describes evening primrose oil as containing omega-6 fatty acids, including GLA. Fish oil is the omega-3 oil, with EPA and DHA. They are different fats.

²²

Do they help eczema?

No. A Cochrane review of 27 trials (1,596 people) found oral evening primrose oil and borage oil no better than placebo. A 12-week trial of borage oil in 140 children and adults found the same.

^{4 14}

Do they help PMS or breast pain?

Reviews found no benefit over placebo for either. For breast pain, a review of 13 trials found evening primrose oil no different from placebo or other treatments. For PMS, two reviews found no benefit.

^{1 17 6}

Do they help menopause hot flashes?

The evidence is mixed. A 2024 review found milder hot flashes under six months but no change in how many or how long. A 2025 review found no significant change in number but shorter hot flashes. Both call the evidence limited.

^{15 11}

Do they help rheumatoid arthritis?

Small older trials suggested less joint pain and swelling, using much more GLA than usual products. Cochrane calls the evidence moderate but NCCIH says insufficient. Do not stop arthritis medicines without a doctor.

^{5 12 22}

Is borage oil safe for the liver?

Borage plants contain alkaloids that can harm the liver. Memorial Sloan Kettering says to use only borage oil certified free of them, and that people with liver problems should avoid borage. One commercial oil tested in a laboratory had alkaloids below the detection limit.

^{21 16}

Can I take them in pregnancy or while breastfeeding?

Memorial Sloan Kettering says borage should not be used in pregnancy or breastfeeding. NCCIH says evening primrose oil may be safe but the evidence is not conclusive. A 2022 review does not recommend it for starting labour. Ask a midwife or doctor.

^{21 22 8}

Do they interact with blood thinners?

Possibly. The Cochrane eczema review cites a study suggesting more bleeding with evening primrose oil in people on warfarin. This is from small studies. Ask a pharmacist or prescriber.

^{4 21}

What are the side effects?

NCCIH says evening primrose oil is generally well tolerated; the most common problems are stomach pain, nausea and diarrhoea. Memorial Sloan Kettering lists headache, belching and loose stools with borage oil.

^{22 21}

Is borage oil better than evening primrose oil?

No head-to-head trial was found. Borage oil has more GLA (about 25% versus about 10%, according to Memorial Sloan Kettering) and also has the liver-alkaloid caution. Each oil was compared with placebo in the trials.

^{21 4}

Do they work for diabetic nerve pain?

Evidence is limited. A 1993 trial of 111 people found GLA slowed nerve changes over a year. Newer trials were small, short or lacked a placebo-only group. Ask a doctor before using anything for nerve pain.

^{10 18 7}

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Editorial transparency

Written by: AlternativeMed editorial team. Research compiled with AI assistance, then checked against the sources listed.
Medical review: None. This page has not been reviewed by a physician or pharmacist.
First published: 2026-10-26
Last substantive update: 2026-10-26
How we research: We read the NCCIH page on evening primrose oil and the Memorial Sloan Kettering page on borage in full, and read the PubMed abstracts for the trials and reviews cited. Only abstracts were read for studies. The NIH Office of Dietary Supplements and LactMed pages could not be read and are marked unread.
How we rate evidence: See "How we rate evidence" in the Evidence tab.
Independence: No product is promoted on this page. No affiliate links are shown. One trial was funded by a supplement company, as noted in the studies.

Sources 22

Each source was opened and checked. Where we read only the abstract, it says so. The small numbers in the text point here.

Ahmad Adni LL, Norhayati MN, Mohd Rosli RR, Muhammad J. A Systematic Review and Meta-Analysis of the Efficacy of Evening Primrose Oil for Mastalgia Treatment.. International Journal of Environmental Research and Public Health. 2021. PMID 34200727. DOI 10.3390/ijerph18126295. (abstract)
Al-Khamees WA, Schwartz MD, Alrashdi S, Algren AD, Morgan BW. Status epilepticus associated with borage oil ingestion.. Journal of Medical Toxicology. 2011. PMID 21387119. DOI 10.1007/s13181-011-0135-9. (abstract)
Ariana S, Amjadi N, Kazemi SN, Ahmadli Z. The Use of Evening Primrose Oil for Cervical Ripening in Low-Risk Women with Term Pregnancy: A Randomized Double-Blinded Controlled Trial.. Complementary Medicine Research. 2024. PMID 38377980. DOI 10.1159/000535585. (abstract)
Bamford JT, Ray S, Musekiwa A, van Gool C, Humphreys R, Ernst E. Oral evening primrose oil and borage oil for eczema.. Cochrane Database of Systematic Reviews. 2013. PMID 23633319. DOI 10.1002/14651858.CD004416.pub2. (abstract)
Cameron M, Gagnier JJ, Chrubasik S. Herbal therapy for treating rheumatoid arthritis.. Cochrane Database of Systematic Reviews. 2011. PMID 21328257. DOI 10.1002/14651858.CD002948.pub2. (abstract)
Dante G, Facchinetti F. Herbal treatments for alleviating premenstrual symptoms: a systematic review.. Journal of Psychosomatic Obstetrics and Gynaecology. 2011. PMID 21171936. DOI 10.3109/0167482X.2010.538102. (abstract)
Gholami A, Koulaeinejad N, Rahimi M. Effects of evening primrose oil on treating painful diabetic neuropathy: a randomized, double-blind, clinical trial.. Journal of Complementary and Integrative Medicine. 2025. PMID 40418820. DOI 10.1515/jcim-2025-0054. (abstract)
Hutcherson TC, Cieri-Hutcherson NE, Lycouras MM, Koehler D, Mortimer M, Schaefer CJ, Costa OS, Bohlmann AL, Singhal MK. Systematic Review of Evening Primrose (Oenothera biennis) Preparations for the Facilitation of Parturition.. Pharmacy (Basel). 2022. PMID 36548328. DOI 10.3390/pharmacy10060172. (abstract)
Jung JY, Kwon HH, Hong JS, Yoon JY, Park MS, Jang MY, Suh DH. Effect of dietary supplementation with omega-3 fatty acid and gamma-linolenic acid on acne vulgaris: a randomised, double-blind, controlled trial.. Acta Dermato-Venereologica. 2014. PMID 24553997. DOI 10.2340/00015555-1802. (abstract)
Keen H, Payan J, Allawi J, Walker J, Jamal GA, Weir AI, Henderson LM, Bissessar EA, Watkins PJ, Sampson M, et al. Treatment of diabetic neuropathy with gamma-linolenic acid. The gamma-Linolenic Acid Multicenter Trial Group.. Diabetes Care. 1993. PMID 8380765. DOI 10.2337/diacare.16.1.8. (abstract)
Larki M, Mohammadi S, Makvandi S. The Effect of Evening Primrose Oil on Menopausal Symptoms Management: A Systematic Review and Meta-Analysis.. Journal of Caring Sciences. 2025. PMID 41883983. DOI 10.34172/jcs.025.33570. (abstract)
Leventhal LJ, Boyce EG, Zurier RB. Treatment of rheumatoid arthritis with gammalinolenic acid.. Annals of Internal Medicine. 1993. PMID 8214997. DOI 10.7326/0003-4819-119-9-199311010-00001. (abstract)
Sharifi M, Nourani N, Sanaie S, Hamedeyazdan S. The effect of Oenothera biennis (Evening primrose) oil on inflammatory diseases: a systematic review of clinical trials.. BMC Complementary Medicine and Therapies. 2024. PMID 38360611. DOI 10.1186/s12906-024-04378-5. (abstract)
Takwale A, Tan E, Agarwal S, Barclay G, Ahmed I, Hotchkiss K, Thompson JR, Chapman T, Berth-Jones J. Efficacy and tolerability of borage oil in adults and children with atopic eczema: randomised, double blind, placebo controlled, parallel group trial.. BMJ. 2003. PMID 14670885. DOI 10.1136/bmj.327.7428.1385. (abstract)
Thevi T, De S, Soe HHK. Evening Primrose Oil for Menopause Hot Flashes: Systematic Review and Meta-Analysis.. Journal of Menopausal Medicine. 2024. PMID 39829189. DOI 10.6118/jmm.23038. (abstract)
Vacillotto G, Favretto D, Seraglia R, Pagiotti R, Traldi P, Mattoli L. A rapid and highly specific method to evaluate the presence of pyrrolizidine alkaloids in Borago officinalis seed oil.. Journal of Mass Spectrometry. 2013. PMID 24130010. DOI 10.1002/jms.3251. (abstract)
Whelan AM, Jurgens TM, Naylor H. Herbs, vitamins and minerals in the treatment of premenstrual syndrome: a systematic review.. Canadian Journal of Clinical Pharmacology. 2009. PMID 19923637. (abstract)
Won JC, Kwon HS, Moon SS, Chun SW, Kim CH, Park IB, Kim IJ, Lee J, Cha BY, Park TS. gamma-Linolenic Acid versus alpha-Lipoic Acid for Treating Painful Diabetic Neuropathy in Adults: A 12-Week, Double-Placebo, Randomized, Noninferiority Trial.. Diabetes and Metabolism Journal. 2020. PMID 31701699. DOI 10.4093/dmj.2019.0099. (abstract)
Zurier RB, Rossetti RG, Jacobson EW, DeMarco DM, Liu NY, Temming JE, White BM, Laposata M. gamma-Linolenic acid treatment of rheumatoid arthritis. A randomized, placebo-controlled trial.. Arthritis and Rheumatism. 1996. PMID 8912502. DOI 10.1002/art.1780391106. (abstract)
da Costa Hime LFC, Carvalho Lopes CM, Roa CL, Zuchelo LTS, Baracat EC, de Andrade J, Soares JM Jr. Is there a beneficial effect of gamma-linolenic acid supplementation on body fat in postmenopausal hypertensive women? A prospective randomized double-blind placebo-controlled trial.. Menopause. 2021. PMID 33534427. DOI 10.1097/GME.0000000000001740. (abstract)
. Memorial Sloan Kettering Cancer Center: Borage, Purported Benefits, Side Effects and More (About Herbs; last updated 31 March 2022). . . (full-text)
. NCCIH: Evening Primrose Oil: Usefulness and Safety (last updated November 2024). . . (full-text)

Where to buy

Check the label first. Whatever you buy, look for these:

The amount of the active ingredient per serving, not just the front-label claim
A third-party testing mark (USP, NSF or ConsumerLab)
Other ingredients and allergens
Ask a pharmacist about interactions with your medicines

Talk to a pharmacist or doctor before you start any supplement, especially if you take medicines. See the Safety tab for interactions.

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Education, not medical advice. This page is for general information. It does not diagnose or treat any condition and is not a substitute for care from a qualified health professional. Natural does not automatically mean safe. Ask a clinician or pharmacist before changing your care, especially if you take medication, are pregnant or breastfeeding, or have a health condition.