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Vitamin B6 for Nausea in Pregnancy and PMS: What Guidelines and Trials Say

What systematic reviews and trials say about vitamin B6 for morning sickness and premenstrual syndrome, the amounts used in studies versus upper limits, and when to call a clinician.

Content last updated . This page has not been medically reviewed.

Quick answer
For morning sickness, vitamin B6 (pyridoxine) has been studied and some trials and reviews report less nausea, but the best Cochrane review found only limited evidence and no strongly supported option. For premenstrual symptoms, the main review was published in 1999, rated the trials low quality, and the NHS says there is not much evidence that supplements work. Neither use is a reason to take B6 without first talking to a midwife, doctor or pharmacist, because amounts used in studies can be higher than official upper limits.

Evidence labels used: promising but limited, mixed, insufficient evidence. All study amounts here are study amounts, not advice.

B6 for premenstrual syndrome (PMS)

The NHS says premenstrual syndrome (PMS) symptoms include mood swings, bloating, breast tenderness, tiredness and headaches, and that complementary therapies and supplements such as vitamin B6, calcium, vitamin D and magnesium may help, but there is not much evidence that they work. [2] It advises checking with a GP or pharmacist if you take medicines before starting regular supplements. [2]
QuestionWhat the source foundStrength
Does B6 improve PMS?A 1999 BMJ systematic review of nine placebo-controlled trials (940 women) found women were more likely to improve overall (odds ratio 2.32) and in depressive symptoms (odds ratio 1.69, four trials, 541 women). It said conclusions were limited by the low quality of most trials and that doses up to 100 mg a day were likely to be of benefit. [12]Mixed; low-quality trials
Newer high-quality trialsProper evidence not found. Our PubMed searches for newer randomized trials of B6 alone for PMS returned mostly multi-ingredient products rather than B6 alone.Insufficient evidence

The 100 mg a day in that 1999 review is the same as the Health Canada upper limit, about eight times the EU limit, and ten times the NHS supplement advice, so it is well above two of the three official figures and equal to the third. [9] [8] [10] The NHS says 200 mg or more a day can cause nerve damage. [10] See PMS and PMDD.

Related

Vitamin B6 profile · Preconception, pregnancy and breastfeeding wellness · All vitamins

Frequently asked questions

Does vitamin B6 help morning sickness?

Some trials report less nausea, such as a 1995 trial using 30 mg a day, but a 2015 Cochrane review found limited evidence overall and no strongly supported intervention. [4] [3]

Is B6 safe in pregnancy?

EFSA applies a 12 mg a day upper limit to pregnant and breastfeeding women. [8] Study amounts may exceed it, so ask your midwife or doctor.

Is doxylamine-pyridoxine the same as B6 alone?

No. It is a combination of an antihistamine and B6. A 2023 trial of it reported a modest symptom benefit and a possible small-for-gestational-age signal needing checking. [6] Your doctor decides if a medicine suits you.

Does B6 help PMS?

A 1999 review of low-quality trials found improvement over placebo, and the NHS says there is not much evidence supplements work. [12] [2]

Can I take B6 for PMS safely?

Official limits vary: 12 mg a day (EU), 10 mg advice (UK), 100 mg (Canada). [8] [10] [9] Ask a clinician or pharmacist, especially if you take other medicines.

More details: evidence, limits and cautions

The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.

When to get medical help first
Pregnancy sickness: the NHS (UK) says to contact your midwife, doctor or urgent care line if you are vomiting and you have very dark urine or have not passed urine in over 8 hours, cannot keep food or fluids down for 24 hours, feel very weak, dizzy or faint, have tummy pain, a high temperature, vomit blood or have lost weight. [1] Severe pregnancy sickness (hyperemesis gravidarum) can lead to dehydration and malnutrition and may need hospital treatment. [1] In an emergency in the US, call 911.

PMS and mood: the NHS says the severe form of PMS, premenstrual dysphoric disorder (PMDD), can include feeling suicidal. [2] If you are in crisis in the US, call or text 988 (Suicide & Crisis Lifeline), or call 911.

B6 for nausea and vomiting in pregnancy
Nausea and vomiting in early pregnancy usually clears by weeks 16 to 20 and, the NHS says, does not put the baby at increased risk. [1] The NHS lists lifestyle steps first (rest, small plain meals, drinking fluids, ginger, acupressure) and, if symptoms are severe, a short course of an anti-sickness medicine that is safe in pregnancy, often an antihistamine. [1] The NHS page we read does not list vitamin B6 among its self-help options.
QuestionWhat the source foundStrength
Overall evidenceA 2015 Cochrane review of 41 trials (5,449 women) found only limited evidence for vitamin B6 and doxylamine-pyridoxine for mild or moderate symptoms and a lack of high-quality evidence for any particular intervention. It says this is not the same as saying they are ineffective. [3]Insufficient evidence
Pyridoxine alone, 30 mg a dayA 1995 trial of 342 women at 17 weeks or less compared pyridoxine with placebo for 5 days. Nausea scores fell more with pyridoxine; the difference in vomiting episodes was not statistically significant. [4]Promising but limited
Meta-analysisA 2023 review of 18 studies reported that pyridoxine, alone or with another active ingredient, improved nausea scores. [5]Promising but limited
Doxylamine-pyridoxine combinationA 2023 trial of 352 women with moderate to severe symptoms found a modest greater drop in the PUQE symptom score over 14 days (mean difference -1.0). The authors said the clinical importance was uncertain, and reported more small-for-gestational-age births with the drug than with placebo (odds ratio 3.8, confidence interval 1.0 to 14.1). [6]Mixed; modest effect, safety signal needs checking

Guidelines: the ACOG (US) bulletin on nausea and vomiting of pregnancy exists, but its abstract does not state a recommendation on B6. [7] The RCOG guideline PDF we downloaded was unreadable (garbled text), and the NICE CKS page returned HTTP 403, so we could not read what those bodies say about B6. Proper evidence not found for a guideline statement on B6 that we could read. Please ask your midwife or doctor what current national guidance says where you live.

Amounts and limits. The 1995 trial used 30 mg a day. [4] The EU upper limit for adults, including pregnant and breastfeeding women, is 12 mg a day (EFSA, 2023). [8] Health Canada lists 100 mg a day (page dated 2025). [9] The NHS advises no more than 10 mg a day in supplements unless a doctor advises otherwise (UK, 2020). [10] The US pregnancy RDA is 1.9 mg a day. [11] Study amounts can therefore exceed some official limits. That is a strong reason to let a clinician decide; see B6 toxicity and upper limits.

Safety and precautions
References
  1. NHS (UK). Vomiting and morning sickness in pregnancy. Page last reviewed 17 April 2024. Read 2026-10-23.
  2. NHS (UK). PMS (premenstrual syndrome). Page last reviewed 18 June 2024. Read 2026-10-23.
  3. Matthews A, et al. Interventions for nausea and vomiting in early pregnancy (Cochrane review). Cochrane Database Syst Rev 2015;(9):CD007575. PMID 26348534. Read 2026-10-23.
  4. Vutyavanich T, Wongtra-ngan S, Ruangsri R. Pyridoxine for nausea and vomiting of pregnancy: a randomized, double-blind, placebo-controlled trial. Am J Obstet Gynecol 1995;173(3 Pt 1):881-4. PMID 7573262. Read 2026-10-23.
  5. Jayawardena R, et al. The effects of pyridoxine (vitamin B6) supplementation in nausea and vomiting during pregnancy: a systematic review and meta-analysis. Arch Gynecol Obstet 2023;308(4):1075-84. PMID 36719452. Read 2026-10-23.
  6. Wu XK, et al. Acupuncture and doxylamine-pyridoxine for nausea and vomiting in pregnancy: a randomized, controlled, 2 x 2 factorial trial. Ann Intern Med 2023;176(7):922-33. PMID 37335994. Read 2026-10-23.
  7. ACOG Committee on Practice Bulletins-Obstetrics. ACOG Practice Bulletin No. 189: nausea and vomiting of pregnancy. Obstet Gynecol 2018;131(1):e15-e30 (abstract). PMID 29266076. Read 2026-10-23.
  8. EFSA Panel on Nutrition, Novel Foods and Food Allergens. Scientific opinion on the tolerable upper intake level for vitamin B6. EFSA Journal 2023;21(5):e08006 (abstract on PubMed). Read 2026-10-23.
  9. Health Canada. Dietary reference intakes tables: Reference values for vitamins. Page dated 2025-11-19. Read 2026-10-23 through a web-fetch tool.
  10. NHS (UK). Vitamins and minerals: B vitamins and folic acid. Page last reviewed 3 August 2020. Read 2026-10-23.
  11. MedlinePlus Medical Encyclopedia (US National Library of Medicine). Vitamin B6. Review date 1/21/2025. Read 2026-10-23.
  12. Wyatt KM, et al. Efficacy of vitamin B-6 in the treatment of premenstrual syndrome: systematic review. BMJ 1999;318(7195):1375-81. PMID 10334745. Read 2026-10-23.
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.