Spices · Spice
Garlic powder
Allium sativum · also called Dehydrated garlic, granulated garlic, ajo en polvo (Spanish)
Garlic powder is dried, ground garlic used to season food. Studies on cholesterol, blood pressure and blood sugar are mostly of garlic supplements, not of garlic powder sprinkled on a meal. Results are small and mixed. The main cautions are allergy, and bleeding or medicine interactions with supplements.
General information, not medical advice. Last substantive update · Not medically reviewed. A named clinician has not signed off on this page. How this page is made
About Garlic powder
Garlic powder is a savoury seasoning. It is a food, not a proven remedy: the health research on garlic is mostly on supplements, and the sources we read describe no problem with a seasoning pinch other than allergy.
What it is
Garlic powder is dried, ground garlic (Allium sativum). It is used in rubs, sauces, soups and spice blends. Garlic is in the same plant group as onion, leek and chives.
USDA data for garlic powder per 100 g: 331 kcal, 16.6 g protein, 9.0 g fibre, 1,190 mg potassium, 5.65 mg iron and 60 mg sodium. A teaspoon is 3.1 g and a tablespoon is 9.7 g, so a teaspoon supplies about 10 kcal, 0.5 g protein, 37 mg potassium and 2 mg sodium. Garlic salt is a different product with added salt. Real products vary.
What the research shows
A 2014 review pooled trials of garlic powder products and found small average drops in cholesterol, blood pressure and fasting glucose. A 2026 review of 108 trials of garlic supplements found smaller drops. A single 12-week trial of garlic powder tablets in 50 people with raised cholesterol found no change.
None of these tested garlic powder used to season food. The abstracts also do not tell us about trial quality, so the certainty is low or mixed.
For colds, the Cochrane review found only one usable trial. For cancer, observational results are mixed and cannot show cause.
Spice versus supplements
Garlic powder tablets, aged extracts, fresh cloves and the spice you shake on food are different products, and results for one may not apply to another. Nearly all benefit and interaction research is on supplements.
Amounts
This page gives no amounts to use. Ask a doctor, pharmacist or dietitian what is right for you, especially if you take medicine, are pregnant or are having surgery.
At a glance
Traditional uses history, not proof
- Used as a savoury seasoning in many cuisines
- Garlic has been used traditionally for many ailments; long use is not proof that it treats any condition
Studied for research
- Cholesterol, mixed certainty (garlic supplements, not seasoning)
- Blood pressure, low certainty (garlic supplements)
- Blood sugar, low certainty (garlic supplements)
- Colds, insufficient evidence
- Cancer risk, low and mixed certainty (observational)
- Heart attacks and strokes, insufficient evidence
Main compounds
- Alliin
- Allicin
- Allyl methyl sulfide
- Potassium
Common forms
- Garlic powder and granulated garlic as seasoning
- Seasoning blends, including garlic salt (a different product)
- Garlic powder tablets and other garlic supplements (the trials used these, not the spice)
Research links: NCCIH: Garlic · 2026 review: garlic supplements and heart risk factors · LactMed: Garlic · Research Library · Genes & Biomarkers Library
What it is and its history
- Accepted scientific name
- Allium sativum
- Naming authority
- L. (GBIF accepted)
- Common names
- Garlic powder (English); Dehydrated garlic (English); Granulated garlic (English); Ajo en polvo (Spanish)
- Family or group
- Amaryllidaceae (GBIF). LactMed groups garlic with onion, leek and chives, which matters for allergy.
- Classification
- Plantae > Tracheophyta > Liliopsida > Asparagales > Amaryllidaceae > Allium > Allium sativum
- Native range
- Not verified from a source read.
- Habitat
- Not verified from a source read.
- What it looks like
- Roots: Not verified.; Stems: Not verified.; Leaves: Not verified.; Flowers: Not verified.; Fruit: Not verified.
- Cultivation
- NCCIH says garlic is cultivated worldwide.
- Harvest and processing
- Dried, ground garlic. Drying and milling details were not read from a source on this build; the existing page summary describes slicing, drying and milling but its sources were not re-opened.
- Look-alikes and adulterants
- Name: Garlic salt; Note: A different seasoning that contains salt, as described by the existing page summary. Check labels.; Name: Garlic supplements (tablets, capsules, aged extract); Note: Different products from the dried spice. Most trials were done with supplements and results for one product may not apply to another (LactMed).; Name: Onion powder, leek, chives; Note: Relatives in the same plant group; LactMed lists them among plants to avoid if allergic to garlic.
- Sustainability and conservation
- Not assessed.
Photographs
Traditional use and history history, not clinical proof
| Tradition or era | Documented use | Source |
|---|---|---|
| Ancient Egypt, Greece and India (as summarised by NCCIH) | NCCIH says ancient writings from Egypt, Greece and India describe garlic being used for headache, pneumonia, throat conditions and stomach and bowel disorders. These are old traditional uses and are not proof that garlic treats any of them. This describes garlic in general; no history of garlic powder was read. | s-nccih-garlic |
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 |
|---|---|---|---|---|
| Alliin PubChem 9576089 | sulfur compound | Bulb Not given in the sources read | LactMed says garlic contains alliin, which the enzyme alliinase turns into allicin. 19 22 | Human data |
| Allicin PubChem 65036 | sulfur compound | Bulb How much allicin remains in garlic powder is not stated in the sources read | LactMed says allicin is thought to be responsible for most of garlic's medicinal properties and odour. 19 21 | Human data |
| Allyl methyl sulfide (and its sulfoxide and sulfone) PubChem 66282 | sulfur compound | Bulb (appears in milk and urine after eating) Not applicable | Garlic-derived volatile products that appear in human breast milk, peaking 1 to 3.5 hours after garlic was eaten; LactMed attributes garlic odour in milk to allyl methyl sulfide. 15 19 23 | Human data |
Mechanisms, receptors and pathways
| Target or pathway | Gene or receptor | What was found | Level |
|---|---|---|---|
| Formation of allicin | Alliinase (enzyme) | Alliin is turned into allicin by the enzyme alliinase (LactMed). Whether and how much of this happens in dried garlic powder was not found in the sources read. 19 | Human data |
| Platelet function | Not specified | LactMed says garlic has anti-platelet effects. A small trial found no impairment of platelet function after raw garlic in a dish, so the effect at food amounts is not shown. 19 14 | Human data |
| Anti-cancer properties of sulfides | Not specified | A 2015 review describes garlic sulfide compounds such as diallyl trisulfide as having anticarcinogenic properties. This is lab-based and not shown in people. 7 | Laboratory research |
Absorption, metabolism and elimination
- Absorption
- Not found for garlic powder.
- Distribution
- Garlic-derived volatile compounds pass into breast milk (18 sets of milk samples).
- Metabolism
- Not found beyond the allyl methyl sulfide, sulfoxide and sulfone products measured in milk.
- Elimination
- Milk levels of garlic compounds were highest 1 to 3.5 hours after eating garlic, with large differences between women.
- Bioavailability
- Not established.
Isolated compounds versus whole extracts
Garlic powder tablets, aged extracts, fresh cloves and the spice shaken on food are different products. The 2014 garlic powder review authors say manufacturing differences markedly change what garlic products contain. LactMed says results from one supplement product may not apply to another. No source read tested the seasoning.
Nutritional composition
Nutrition from USDA FoodData Central (Spices, garlic powder, FDC 171325, SR Legacy April 2018, read 2026-10-26 from the project's saved copy of the data). Per 100 g: 331 kcal, 16.6 g protein, 0.73 g fat, 72.7 g carbohydrate, 9.0 g fibre, 79 mg calcium, 5.65 mg iron, 77 mg magnesium, 1,190 mg potassium, 60 mg sodium, 2.99 mg zinc, 23.9 micrograms selenium, 0.979 mg manganese, 0.533 mg copper, 1.2 mg vitamin C, 0.4 micrograms vitamin K. USDA household portions: 1 teaspoon = 3.1 g and 1 tablespoon = 9.7 g. One teaspoon (3.1 g), calculated from those values: about 10 kcal, 0.3 g fibre, 0.5 g protein, 37 mg potassium, 2 mg sodium, 0.2 mg iron. A teaspoon is mostly flavour; these are small amounts and no daily-value comparison was made. Real products vary.
1 mixed findings3 low certainty3 not enough evidence
What was looked at
The 7 benefits and uses checked for Garlic powder, each with how strong the evidence is. Tap one to open it.
- Cholesterol (total and LDL)Mixed findings
- Blood pressureLow certainty
- Heart attacks and strokesNot enough evidence
- Blood sugarLow certainty
- ColdsNot enough evidence
- Cancer riskLow certainty
- Preventing pre-eclampsia in pregnancyNot enough evidence
Lab markers tracked in the studies
LDL and total cholesterolSystolic and diastolic blood pressureFasting blood glucoseNumber of common colds
What is Garlic powder good for?
The main studied uses and how strong the human evidence is for each. Nearly all of the research is on garlic supplements, not on garlic powder used as a seasoning.
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.
Cholesterol (total and LDL)
Mixed findingsPooled trials of garlic supplements, including garlic powder tablets, show a small average drop in total and LDL cholesterol. One well-controlled trial of garlic powder tablets found no change. None of this tests garlic powder used to season food.
4 studiesGarlic powder tablets and other garlic supplements. Not garlic powder…
Studies, doses and limits
What the trials found
A 2014 meta-analysis of randomised trials of garlic powder (22 trials for total cholesterol, 17 for LDL) found total cholesterol 15.83 mg/dL lower and LDL 8.11 mg/dL lower on average. A 2026 meta-analysis of 108 trials (7,137 adults) of garlic supplementation found total cholesterol 10.21 mg/dL lower, LDL 5.90 mg/dL lower and HDL 2.18 mg/dL higher. NCCIH says garlic supplements may lower total and LDL cholesterol to a small extent in people with high cholesterol. A 12-week trial of 50 people with raised cholesterol using garlic powder tablets found no significant change.
Results
Small average improvements in blood-fat numbers in pooled supplement trials; one placebo-controlled garlic powder trial was null. No source read tested garlic powder as a seasoning.
Effect sizes as reported
Garlic powder (2014 review): total cholesterol -15.83 mg/dL (95% CI -26.64 to -4.63), LDL -8.11 mg/dL (-15.44 to -1.16). All garlic supplements (2026 review, 108 trials): total cholesterol -10.21 mg/dL (-13.69 to -6.74), LDL -5.90 (-10.51 to -1.29), HDL +2.18 (1.49 to 2.87), triglycerides -5.82 (-8.16 to -3.49).
Why this rating
Mixed. Two meta-analyses point to a small lowering and NCCIH agrees, but the one large placebo-controlled garlic powder tablet trial read was null, the abstracts do not give trial quality or consistency, and the results are for tablets and supplements. Nothing shows an effect for garlic powder used in cooking, so that use is rated insufficient.
Form and dose studied
Garlic powder tablets and other garlic supplements. Not garlic powder as a seasoning.
Who was studied
Mostly adults, many with raised cholesterol or other risk factors; the 2026 authors say benefits were clearer in people with unfavourable starting values.
Limits
Abstracts only. Lab numbers are not heart attacks or strokes. The 2026 abstract does not say which garlic forms were pooled.
Why researchers looked
Garlic is a common food, and people ask whether adding more of it, or taking it as tablets, helps blood fats.
Traditional use
Garlic powder is dried, ground garlic used as a seasoning. Long use as food is not proof that it treats any condition.
Proposed mechanism Unknown
Not established by the sources read.
A proposed mechanism does not show that the effect happens in people.
Garlic supplements may add to bleeding risk and interact with some medicines; see the Safety tab. Do not replace cholesterol medicine.
Blood pressure
Low certaintyPooled trials of garlic supplements show a small average drop in blood pressure. This is for tablets and capsules, not for garlic powder as a seasoning.
3 studiesGarlic powder tablets and other supplements.
Studies, doses and limits
What the trials found
The 2014 meta-analysis of garlic powder trials (9 trials for systolic and 10 for diastolic pressure) found systolic pressure 4.34 mmHg lower and diastolic 2.36 mmHg lower on average. The 2026 meta-analysis of garlic supplementation found systolic 3.71 mmHg lower and diastolic 1.97 mmHg lower. NCCIH says limited evidence suggests garlic supplements may lower blood pressure to a small extent in people with high blood pressure.
Results
Small average drops in supplement trials. The intervals for the garlic powder review nearly reach zero.
Effect sizes as reported
Garlic powder (2014): systolic -4.34 mmHg (95% CI -8.38 to -0.29), diastolic -2.36 (-4.56 to -0.15). All garlic supplements (2026): systolic -3.71 (-5.07 to -2.36), diastolic -1.97 (-2.86 to -1.08).
Why this rating
Low. Small average changes, wide intervals in the garlic powder review, abstract-only reading, NCCIH calls the evidence limited, and none of it is for seasoning amounts.
Form and dose studied
Garlic powder tablets and other supplements.
Who was studied
Adults in trials; NCCIH refers to people with high blood pressure.
Limits
Abstracts only. Blood pressure numbers are not strokes or heart attacks. Not a replacement for prescribed treatment.
Why researchers looked
Garlic is often promoted for heart health, so trials have measured blood pressure.
Traditional use
Garlic powder is dried, ground garlic used as a seasoning. Long use as food is not proof that it treats any condition.
Proposed mechanism Unknown
Not established by the sources read.
A proposed mechanism does not show that the effect happens in people.
Ask your doctor before using supplements with blood pressure medicine.
Heart attacks and strokes
Not enough evidenceNo source read shows that garlic powder or garlic supplements prevent heart attacks or strokes. The trials measured blood tests and blood pressure, not these events.
2 studiesNot applicable.
Studies, doses and limits
What the trials found
The two meta-analyses read report cholesterol, blood sugar and blood pressure measures, not heart attacks or strokes. The NCCIH page does not describe any trial showing fewer heart events.
Results
No outcome trial was found in the sources read.
Effect sizes as reported
Not available.
Why this rating
Insufficient. The sources read measure risk markers, not heart attacks or strokes.
Limits
We did not search for a garlic outcome trial beyond the sources named here.
Why researchers looked
Lower cholesterol and blood pressure are hoped to mean fewer heart problems, so people ask whether garlic does.
Traditional use
Garlic powder is dried, ground garlic used as a seasoning. Long use as food is not proof that it treats any condition.
Proposed mechanism Unknown
Not applicable.
A proposed mechanism does not show that the effect happens in people.
None specific.
Blood sugar
Low certaintyPooled trials of garlic supplements show a small average drop in fasting blood sugar. It is a change in a lab number, and it is not shown for garlic powder in food.
4 studiesGarlic powder tablets and other supplements.
Studies, doses and limits
What the trials found
The garlic powder review (4 trials) found fasting glucose 17.30 mg/dL lower. The 2026 review found fasting glucose 2.77 mg/dL lower, insulin 1.74 mU/L lower and insulin resistance (HOMA-IR) 0.37 lower. A 2015 meta-analysis of 7 trials (513 people) found a lower fasting glucose; after-meal glucose and HbA1c could not be pooled. NCCIH says garlic supplements may reduce blood sugar to a small extent in people with diabetes.
Results
Small average drops in fasting glucose in supplement trials. The garlic powder estimate is very wide and nearly reaches zero.
Effect sizes as reported
Garlic powder: -17.30 mg/dL (95% CI -34.41 to -0.18), 4 trials. All garlic supplements (2026): -2.77 mg/dL (-5.25 to -0.28). 2015 review: SMD -1.67 (-2.80 to -0.55).
Why this rating
Low. Small trial numbers, very different estimates between reviews (-17 versus -3 mg/dL), abstract-only reading, a fasting lab number and not diabetes outcomes, and supplements not food.
Form and dose studied
Garlic powder tablets and other supplements.
Who was studied
Adults in trials, including people with diabetes (NCCIH).
Limits
HbA1c and after-meal glucose were not pooled in the 2015 review. People with diabetes should not change treatment on their own.
Why researchers looked
Garlic has been studied for blood sugar in people with and without diabetes.
Traditional use
Garlic powder is dried, ground garlic used as a seasoning. Long use as food is not proof that it treats any condition.
Proposed mechanism Unknown
Not established by the sources read.
A proposed mechanism does not show that the effect happens in people.
If you take diabetes medicine, ask a clinician before using garlic supplements.
Colds
Not enough evidenceThere is not enough evidence. A Cochrane review found only one usable trial of a garlic supplement and said claims rest largely on poor-quality evidence.
2 studiesA supplement with a stated allicin content; not garlic powder in food.
Studies, doses and limits
What the trials found
Cochrane (2014) found 1 qualifying trial of 146 people given a garlic supplement (180 mg allicin content) or placebo for 12 weeks: 24 colds versus 65 and 111 versus 366 days of illness; time to recovery was similar. NCCIH says a 2022 review found only two small studies with weaknesses.
Results
A single trial suggested fewer colds; the reviewers say more studies are needed.
Effect sizes as reported
24 versus 65 colds (P<0.001); recovery 4.63 versus 5.63 days.
Why this rating
Insufficient. One trial, self-reported colds, and the Cochrane reviewers conclude evidence is insufficient.
Form and dose studied
A supplement with a stated allicin content; not garlic powder in food.
Who was studied
Adults in one trial.
Limits
Only one trial met the review criteria. Adverse effects in it were rash and odour.
Why researchers looked
Garlic is promoted for immune support in cold and flu season.
Traditional use
Garlic powder is dried, ground garlic used as a seasoning. Long use as food is not proof that it treats any condition.
Proposed mechanism Unknown
Not established by the sources read.
A proposed mechanism does not show that the effect happens in people.
See the Safety tab.
Cancer risk
Low certaintyStudies of people who eat more garlic give mixed results. Cohort studies and a pooled analysis found no clear link, and these studies cannot show cause.
4 studiesGarlic as eaten (all forms together) and supplements.
Studies, doses and limits
What the trials found
A 2020 meta-analysis of 11 observational studies linked the highest garlic intake to lower colorectal cancer risk (RR 0.80, 95% CI 0.69 to 0.91), but cohort studies showed no difference (RR 0.99, 0.80 to 1.23) and heterogeneity was high. A 2015 meta-analysis (mostly case-control studies) linked high garlic intake to lower gastric cancer risk (OR 0.49, 0.38 to 0.62). A 2021 meta-analysis found no significant link between allium vegetables (RR 0.97) or garlic supplements (RR 0.97) and overall cancer risk. NCCIH says consuming garlic does not seem to reduce the risk of stomach cancer and that it is uncertain for colorectal cancer.
Results
Mixed. Sources disagree on stomach cancer. The stronger study designs (cohorts, pooled allium analysis) showed no link.
Effect sizes as reported
Colorectal RR 0.80 overall, 0.99 in cohorts. Gastric OR 0.49 (high intake). All cancers RR 0.97 (allium vegetables and garlic supplements).
Why this rating
Low and mixed. Observational studies cannot show cause, results differ by study design, and NCCIH reaches a different conclusion on stomach cancer. Garlic powder was not separated from other garlic in any abstract read.
Form and dose studied
Garlic as eaten (all forms together) and supplements.
Who was studied
Adults in population studies.
Limits
Abstracts only. Intake was measured in different ways across studies.
Why researchers looked
Garlic contains sulfur compounds that are studied in the lab for effects on cancer cells; population studies ask whether eating more garlic goes with less cancer.
Traditional use
Garlic powder is dried, ground garlic used as a seasoning. Long use as food is not proof that it treats any condition.
Proposed mechanism Laboratory research
A 2015 review names sulfide compounds in garlic, such as diallyl trisulfide, as having anticarcinogenic properties in laboratory work. This is lab evidence, not proven in people.
A proposed mechanism does not show that the effect happens in people.
None specific. Not a substitute for cancer screening.
Preventing pre-eclampsia in pregnancy
Not enough evidenceThere is not enough evidence. A Cochrane review found one small trial of uncertain quality with no clear difference.
1 studiesForm not stated in the abstract.
Studies, doses and limits
What the trials found
Cochrane (2006) found one trial of 100 women: no clear difference in pre-eclampsia (RR 0.78, 95% CI 0.31 to 1.93) or gestational hypertension (RR 0.50, 0.25 to 1.00). Women given garlic were more likely to report odour (RR 8.50, 2.07 to 34.88).
Results
No clear benefit; the reviewers do not recommend increased garlic intake for preventing pre-eclampsia on this evidence.
Effect sizes as reported
Pre-eclampsia RR 0.78 (0.31-1.93).
Why this rating
Insufficient. One small trial of uncertain quality.
Form and dose studied
Form not stated in the abstract.
Who was studied
Pregnant women in one trial.
Limits
Another study was excluded because 29% of women were lost to follow-up.
Why researchers looked
Because garlic may lower blood pressure, it was tested to prevent high blood pressure in pregnancy.
Traditional use
Garlic powder is dried, ground garlic used as a seasoning. Long use as food is not proof that it treats any condition.
Proposed mechanism Unknown
Not established.
A proposed mechanism does not show that the effect happens in people.
Ask your midwife or doctor about garlic supplements in pregnancy.
Connections to the rest of health
How Garlic powder 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
B. Body systems
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| Cardiovascular System | Biological association | Mixed findings | Studied for: Cholesterol (total and LDL) Studied for: Blood pressure | 8 2 6 20 |
| Endocrine System | Biological association | Low certainty | Studied for: Blood sugar | 8 2 5 20 |
| Immune System | Biological association | Not enough evidence | Studied for: Colds | 9 20 |
| Respiratory System | Biological association | Not enough evidence | Studied for: Colds | 9 20 |
| Digestive System | Biological association | Low certainty | Studied for: Cancer risk | 17 7 16 20 |
| Reproductive System | Biological association | Not enough evidence | Studied for: Preventing pre-eclampsia in pregnancy | 11 |
I. Biomarkers
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| LDL and total cholesterol | Biological association | Mixed findings | Measured in trials: lowered. A lab change is not the same as a health benefit. | 8 2 6 |
| Systolic and diastolic blood pressure | Biological association | Low certainty | Measured in trials: lowered. A lab change is not the same as a health benefit. | 8 2 |
| Fasting blood glucose | Biological association | Low certainty | Measured in trials: lowered. A lab change is not the same as a health benefit. | 8 2 5 |
| Number of common colds | Biological association | Not enough evidence | Measured in trials: lowered. A lab change is not the same as a health benefit. | 9 |
K. Biological pathways
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| Potassium | Preliminary mechanism | Human | Dried garlic is concentrated, so potassium per 100 g is high (1,190 mg), but a teaspoon supplies only about 37 mg. | 24 |
L. Active compounds
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| Alliin | Biological association | Human | LactMed says garlic contains alliin, which the enzyme alliinase turns into allicin. Preparation or compound: Bulb |
19 22 |
| Allicin | Biological association | Human | LactMed says allicin is thought to be responsible for most of garlic's medicinal properties and odour. Preparation or compound: Bulb |
19 21 |
| Allyl methyl sulfide (and its sulfoxide and sulfone) | Biological association | Human | Garlic-derived volatile products that appear in human breast milk, peaking 1 to 3.5 hours after garlic was eaten; LactMed attributes garlic odour in milk to allyl methyl sulfide. Preparation or compound: Bulb (appears in milk and urine after eating) |
15 19 23 |
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 4 lab markers
Tap a number to show only those markers. Counts are markers, not people.
The evidence
The research centre for Garlic powder. Every record here was checked against PubMed or the publisher's page; we never list a study we have not verified.
Evidence by outcome
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 started from our existing garlic powder summary, re-checked nutrition against USDA FoodData Central data, read the NCCIH and LactMed pages and searched PubMed for reviews, trials and case reports. Only abstracts were read for studies. Items we could not verify are flagged in the research gaps.
Study library: every study we checked 25
| Study | Design | People | Product, dose, length | Result |
|---|---|---|---|---|
| Barrere 2020 Optimization of Salmonella detection in garlic, onion, cinnamon, red chili pepper powders and green tea International Journal of Food Microbiology · PMID 31733520 · DOI |
Laboratory method lab |
Laboratory samples of dried spices (including garlic powder) spiked with Salmonella | Garlic powder and other dried spices in a lab test Garlic Trial detail, not advice Lab method |
The abstract opens by saying Salmonella has caused many outbreaks related to spice consumption. Because spices can hinder recovery of the germ, the authors improved a lab broth so Salmonella could be found in garlic powder, onion, cinnamon, chili and tea samples. Method paper (Not applicable) Methods, limits and fundingOutcomes: Ability to detect Salmonella Limitations: A lab-method paper. It does not say how often garlic powder is contaminated. Funding and conflicts: Authors declare no conflicts. Read: abstract |
| Behrouz 2026 Effects of Garlic Supplementation on Cardiovascular Risk Factors in Adults: A Comprehensive Updated Systematic Review and Meta-Analysis of Randomized Controlled Trials Nutrition Reviews · PMID 40580481 · DOI |
Systematic review meta analysis |
7137 108 randomised trials, 7,137 adults (searched to June 2024) |
Garlic supplementation in several forms (the abstract does not list which forms) Garlic Trial detail, not advice · vs Control groups in each trial |
Garlic supplementation lowered triglycerides, total and LDL cholesterol, fasting glucose, insulin, blood pressure and some inflammation markers on average, and raised HDL cholesterol slightly. It did not change apolipoprotein A-1, apolipoprotein B, ALT, interleukin-6, body weight or adiponectin. The authors say benefits were clearer in adults with unfavourable starting values and call for larger, longer, better trials. Total cholesterol -10.21 mg/dL; LDL -5.90 mg/dL; HDL +2.18 mg/dL; triglycerides -5.82 mg/dL; fasting glucose -2.77 mg/dL; systolic -3.71 mmHg; diastolic -1.97 mmHg (95% CI: total cholesterol -13.69 to -6.74; LDL -10.51 to -1.29; HDL 1.49 to 2.87; triglycerides -8.16 to -3.49; glucose -5.25 to -0.28; systolic -5.07 to -2.36; diastolic -2.86 to -1.08) Methods, limits and fundingOutcomes: Blood fats, blood sugar, insulin, blood pressure, liver enzymes, inflammation and oxidative stress markers Limitations: Abstract only. Forms, doses and trial quality are not given in the abstract. Changes in lab numbers are not the same as fewer heart attacks or strokes. Many pooled trials are small. Supplements, not seasoning. Funding and conflicts: Funding and conflicts not stated in the abstract. Read: abstract |
| Borrelli 2007 Garlic (Allium sativum L.): adverse effects and drug interactions in humans Molecular Nutrition and Food Research · PMID 17918162 · DOI |
Systematic review |
Review of clinical trials and case reports of garlic use | Garlic in several forms Garlic Trial detail, not advice |
Garlic breath and body odour are the most common and best-documented complaints. Case reports describe allergic reactions (contact dermatitis, hives, angioedema, pemphigus, anaphylaxis, photoallergy), altered platelet function and coagulation with a possible bleeding risk, and burns when fresh garlic is applied to skin, especially under dressings. Garlic may enhance anticoagulants such as warfarin and may reduce the effect of saquinavir. Qualitative review (Not applicable) Methods, limits and fundingOutcomes: Adverse effects and drug interactions Limitations: Narrative review of case reports and trials of mixed quality; does not separate food amounts from supplements in the abstract. Funding and conflicts: Funding and conflicts not stated in the abstract. Read: abstract |
| Hitl 2021 Garlic burn injuries - a systematic review of reported cases American Journal of Emergency Medicine · PMID 33571752 · DOI |
Systematic review |
39 32 articles describing 39 patients with burns from raw garlic put on the skin |
Raw garlic applied to skin or mucous membranes Garlic Trial detail, not advice |
In most cases garlic caused second-degree burns, and some caused dead tissue. Legs were the most common site. The authors advise against putting fresh garlic on skin or mucous membranes. Mostly second-degree burns (Not applicable) Methods, limits and fundingOutcomes: Burn severity and treatment Limitations: Case reports only; about fresh garlic on the skin, not eating garlic or garlic powder. Funding and conflicts: Authors declare no conflicts. Read: abstract |
| Hou 2015 Garlic intake lowers fasting blood glucose: meta-analysis of randomized controlled trials Asia Pacific Journal of Clinical Nutrition · PMID 26693740 · DOI |
Systematic review meta analysis |
513 7 randomised trials, 513 people |
Garlic or garlic extracts (forms not itemised in the abstract) Garlic Trial detail, not advice · vs Placebo or control |
Pooled analysis showed lower fasting glucose with garlic. Only 1 trial reported after-meal glucose and 2 reported HbA1c, so those could not be pooled. The authors call for more trials. Standardised mean difference -1.67 for fasting glucose, P=0.004 (SMD 95% CI -2.80 to -0.55) Methods, limits and fundingOutcomes: Fasting blood glucose; after-meal glucose and HbA1c could not be pooled Limitations: Abstract only; small pool; standardised units, not mg/dL; forms unclear. Funding and conflicts: Funding and conflicts not stated in the abstract. Read: abstract |
| Isaacsohn 1998 Garlic powder and plasma lipids and lipoproteins: a multicenter, randomized, placebo-controlled trial Archives of Internal Medicine · PMID 9625398 · DOI |
Controlled trial |
50 50 adults with raised cholesterol (28 garlic powder, 22 placebo), mean age 58 and 57 |
Garlic powder tablets (Kwai brand), 300 mg three times a day with meals Garlic Trial detail, not advice 12 weeks · vs Identical-looking placebo tablet |
No significant change in blood fats in either group and no significant difference between them. The authors concluded the garlic powder tablets were ineffective for lowering cholesterol in these patients. No significant lipid or lipoprotein change versus placebo (Not reported in the abstract) Methods, limits and fundingOutcomes: Total, LDL and HDL cholesterol and triglycerides after 12 weeks Limitations: Small trial; one brand of tablet; 12 weeks only. Its null result conflicts with the pooled results above. Funding and conflicts: Abstract lists non-US-government research support; the brand is named in the abstract but who paid is not stated. Read: abstract |
| Kodali 2015 Meta-analysis: Does garlic intake reduce risk of gastric cancer? Nutrition and Cancer · PMID 25411831 · DOI |
Systematic review meta analysis |
14 case-control studies, 2 randomised studies and 1 cohort study; 8,621 cases and 14,889 controls | Garlic intake (amounts and forms varied) Garlic Trial detail, not advice · vs Lower or no garlic intake |
High, low and any garlic intake were each linked to lower gastric cancer risk. The authors note wide variation in how intake was measured and call for better studies. High intake OR 0.49; low intake OR 0.75; any intake OR 0.77 (95% CI: high 0.38-0.62; low 0.58-0.97; any 0.60-1.00) Methods, limits and fundingOutcomes: Gastric cancer risk Limitations: Mostly case-control studies, which cannot show cause. The NCCIH page says consuming garlic does not seem to reduce stomach cancer risk, so sources differ. Funding and conflicts: Funding and conflicts not stated in the abstract. Read: abstract |
| Kwak 2014 Garlic powder intake and cardiovascular risk factors: a meta-analysis of randomized controlled clinical trials Nutrition Research and Practice · PMID 25489404 · DOI |
Systematic review meta analysis |
Adults in randomised trials of garlic powder (22 trials for total cholesterol, 17 LDL, 18 HDL, 4 fasting glucose, 9 systolic and 10 diastolic blood pressure) | Garlic powder (supplement products in trials; searched to May 2014) Garlic Trial detail, not advice · vs Placebo or control in each trial (not detailed in the abstract) |
Garlic powder lowered total cholesterol, LDL cholesterol, fasting glucose and blood pressure on average. The authors say they restricted the review to garlic powder because manufacturing differences change what garlic products contain. Total cholesterol -15.83 mg/dL; LDL -8.11 mg/dL; fasting glucose -17.30 mg/dL; systolic -4.34 mmHg; diastolic -2.36 mmHg (95% CI: total cholesterol -26.64 to -4.63 mg/dL; LDL -15.44 to -1.16; glucose -34.41 to -0.18; systolic -8.38 to -0.29 mmHg; diastolic -4.56 to -0.15) Methods, limits and fundingOutcomes: Total, LDL and HDL cholesterol, fasting blood glucose, systolic and diastolic blood pressure Limitations: Abstract only. The glucose result rests on 4 trials and its interval almost reaches zero. Heterogeneity and trial quality are not given in the abstract. These are tablets or capsules, not garlic powder used in cooking. Funding and conflicts: Funding and conflicts not stated in the abstract. Read: abstract |
| Lissiman 2014 Garlic for the common cold Cochrane Database of Systematic Reviews · PMID 25386977 · DOI |
Systematic review |
146 Randomised trials of garlic for preventing or treating the common cold; only 1 trial (146 people) qualified |
Garlic supplement containing 180 mg allicin, once daily Garlic Trial detail, not advice 12 weeks · vs Placebo |
The one trial reported 24 colds in the garlic group versus 65 on placebo, and days of illness 111 versus 366. Recovery time was similar (4.63 versus 5.63 days). The reviewers say there is insufficient evidence and claims rely on poor-quality evidence. 24 versus 65 colds (P<0.001); 111 versus 366 days of illness (Not reported in the abstract) Methods, limits and fundingOutcomes: Number of colds, days of illness, days to recovery Limitations: Only one trial; colds were self-reported; the reviewers conclude evidence is insufficient. Adverse effects were rash and odour. Funding and conflicts: Cochrane conflict statement: none known for the authors; one author received support for methods training, not for this review. Read: abstract |
| Ma 2012 Anaphylaxis induced by ingestion of raw garlic Foodborne Pathogens and Disease · PMID 22817136 · DOI |
Case report |
1 One patient with anaphylaxis after eating raw garlic |
Raw garlic versus cooked garlic extracts tested in the lab Garlic Trial detail, not advice · vs Cooked garlic extract |
Specific IgE to garlic was 8.16 kUA/L. IgE-binding proteins were found only in raw garlic extract, because heating broke most allergens into small fragments. The authors say raw garlic can cause life-threatening anaphylaxis, and suggest people allergic to garlic might tolerate cooked garlic. One case; allergen bands detected only in raw extract (Not applicable) Methods, limits and fundingOutcomes: Garlic-specific IgE; allergen bands in raw versus heated garlic Limitations: A single case. The tolerance of cooked garlic is the authors' hypothesis, not a tested result. Does not tell us about dried garlic powder. Funding and conflicts: Not stated. Read: abstract |
| Meher 2006 Garlic for preventing pre-eclampsia and its complications Cochrane Database of Systematic Reviews · PMID 16856110 · DOI |
Systematic review |
100 1 randomised trial of 100 pregnant women (of uncertain quality) |
Garlic (form not stated in the abstract) Garlic Trial detail, not advice · vs Placebo |
No clear difference in high blood pressure of pregnancy or pre-eclampsia. Women given garlic were more likely to report odour; other side effects did not differ significantly. The reviewers found insufficient evidence to recommend garlic for preventing pre-eclampsia. Pre-eclampsia RR 0.78; gestational hypertension RR 0.50; odour RR 8.50 (95% CI: pre-eclampsia 0.31-1.93; gestational hypertension 0.25-1.00; odour 2.07-34.88) Methods, limits and fundingOutcomes: Gestational high blood pressure, pre-eclampsia, side effects Limitations: One small trial of uncertain quality; another was excluded for 29% loss to follow-up. Funding and conflicts: Cochrane conflict statement: none known. Read: abstract |
| Mohammed Abdul 2008 Pharmacodynamic interaction of warfarin with cranberry but not with garlic in healthy subjects British Journal of Pharmacology · PMID 18516070 · DOI |
Controlled trial |
12 12 healthy men with known CYP2C9 and VKORC1 genotype |
Garlic pre-treatment (form not stated in the abstract) before a single warfarin dose Garlic Trial detail, not advice 2 weeks of pre-treatment · vs Warfarin alone, and warfarin after cranberry (3-way crossover) |
Garlic did not significantly change warfarin pharmacokinetics or pharmacodynamics. Cranberry increased the INR response by 30%. Both herbs showed some signs of genotype-dependent effects that the authors say deserve more study. No significant change with garlic (Not reported in the abstract) Methods, limits and fundingOutcomes: Warfarin levels, INR, platelet aggregation, clotting factor activity Limitations: Small, healthy men, single warfarin dose, open-label. Does not show safety in patients taking warfarin long-term. Funding and conflicts: Funding and conflicts not stated in the abstract. Read: abstract |
| Piscitelli 2002 The effect of garlic supplements on the pharmacokinetics of saquinavir Clinical Infectious Diseases · PMID 11740713 · DOI |
Controlled trial |
10 10 healthy volunteers |
Garlic caplets twice daily (41 doses) with the HIV medicine saquinavir Garlic Trial detail, not advice 21 days of garlic; saquinavir on 3 separate 4-day periods · vs The same people on saquinavir before garlic and after a washout |
With garlic, saquinavir exposure (AUC) fell by 51%, trough by 49% and Cmax by 54%. After a 10-day washout levels returned to only 60-70% of baseline. The authors advise caution combining garlic supplements with saquinavir when it is the only protease inhibitor. AUC -51%; trough -49%; Cmax -54% (Not reported in the abstract) Methods, limits and fundingOutcomes: Saquinavir blood levels (AUC, trough, Cmax) Limitations: Ten healthy people; garlic supplement caplets, not food. Saquinavir is an older HIV medicine, now usually given with a booster. Funding and conflicts: Funding and conflicts not stated in the abstract. Read: abstract |
| Scharbert 2007 Garlic at dietary doses does not impair platelet function Anesthesia and Analgesia · PMID 17959943 · DOI |
Controlled trial |
18 18 healthy volunteers (a one-week follow-up in 5 of them) |
Raw garlic (4.2 g) eaten in Greek tsatsiki Garlic Trial detail, not advice Single dose, tested 5 hours later; 5 volunteers ate it daily for 1 week · vs Tsatsiki without garlic (placebo), randomised crossover |
Platelet function was not impaired by single or repeated eating of tsatsiki with raw garlic in any test. The authors concluded dishes with socially acceptable amounts of raw garlic are unlikely to raise bleeding risk around surgery, and that combined effects with platelet-inhibiting drugs need study. No impairment in any platelet test (Not reported in the abstract) Methods, limits and fundingOutcomes: Platelet function (PFA-100, impedance aggregometry, thrombelastography) Limitations: Small; healthy volunteers; raw garlic in a dish, not garlic powder and not garlic supplements. The follow-up had only 5 people. Funding and conflicts: Funding and conflicts not stated in the abstract. Read: abstract |
| Scheffler 2019 Quantification of volatile metabolites derived from garlic in human breast milk Food Chemistry · PMID 30372984 · DOI |
Observational |
18 18 sets of human milk samples (one before and three after garlic eating) |
Garlic eaten by the mothers (form and amount not stated in the abstract) Garlic Trial detail, not advice Samples within hours · vs Sample before garlic |
The compounds were highest 1 to 3.5 hours after garlic was eaten, with big differences between women. Mothers' garlic eating has been reported to be linked to later garlic acceptance by infants. Peak 1-3.5 hours after eating (Not applicable) Methods, limits and fundingOutcomes: Garlic-derived smelly compounds in milk (allyl methyl sulfide, sulfoxide and sulfone) Limitations: Measures what passes into milk, not harm or benefit to the baby. Funding and conflicts: Not stated in the abstract. Read: abstract |
| Zhang 2021 Allium Vegetables, Garlic Supplements, and Risk of Cancer: A Systematic Review and Meta-Analysis Frontiers in Nutrition · PMID 35402472 · DOI |
Systematic review meta analysis |
22 studies of allium vegetables and 10 studies of garlic supplements | Allium vegetables as food; garlic supplements Garlic Trial detail, not advice · vs Highest versus lowest intake |
High allium vegetable intake was not significantly linked to cancer risk, and neither were garlic supplements. The authors found no evidence that higher consumption reduced cancer risk and say the finding needs validation. Allium vegetables RR 0.97; garlic supplements RR 0.97 (95% CI: 0.92-1.03 and 0.84-1.12) Methods, limits and fundingOutcomes: Overall cancer risk Limitations: Pools all cancers together; mostly observational. Funding and conflicts: Authors declare no commercial or financial relationships. Read: abstract |
| Zhou 2020 Garlic intake and the risk of colorectal cancer: A meta-analysis Medicine (Baltimore) · PMID 31895803 · DOI |
Systematic review meta analysis |
11 observational studies (12,558 cases) of garlic intake and colorectal cancer | Garlic as eaten (food intake categories) Garlic Trial detail, not advice · vs Lowest versus highest garlic intake |
Overall, the highest garlic intake was linked to lower risk of colorectal cancer. Case-control studies showed lower risk, but cohort studies showed no difference. There was substantial heterogeneity. Overall RR 0.80; case-control RR 0.71; cohorts RR 0.99 (95% CI: overall 0.69-0.91; case-control 0.60-0.84; cohorts 0.80-1.23; I-squared 68.3%) Methods, limits and fundingOutcomes: Colorectal cancer risk Limitations: Observational. The cohort studies, which are less open to recall bias, found no link. Cannot show cause. Funding and conflicts: Authors declare no conflicts. Read: abstract |
| s-gbif-allium-sativum GBIF Backbone Taxonomy: Allium sativum L. (usageKey 2856681) · Source |
Reference database n/a |
Methods, limits and fundingRead: full-text | ||
| s-lactmed-garlic LactMed (NIH): Garlic · Source |
Health agency n/a |
Methods, limits and fundingRead: full-text | ||
| s-nccih-garlic NCCIH: Garlic - Usefulness and Safety · Source |
Health agency n/a |
Methods, limits and fundingRead: full-text | ||
| s-pubchem-allicin PubChem: Allicin (CID 65036) · Source |
Reference database n/a |
Methods, limits and fundingRead: full-text | ||
| s-pubchem-alliin PubChem: Alliin (CID 9576089) · Source |
Reference database n/a |
Methods, limits and fundingRead: full-text | ||
| s-pubchem-ams PubChem: Allyl methyl sulfide (CID 66282) · Source |
Reference database n/a |
Methods, limits and fundingRead: full-text | ||
| s-usda-fdc-171325 USDA FoodData Central: Spices, garlic powder (FDC 171325) · Source |
Reference database n/a |
Methods, limits and fundingRead: full-text | ||
| van der Walt 2010 Work-related allergy and asthma in spice mill workers - The impact of processing dried spices on IgE reactivity patterns International Archives of Allergy and Immunology · PMID 20150745 · DOI |
Case series |
3 3 spice mill workers with work-related asthma after prolonged exposure to inhalable spice dust |
Garlic, onion and chili pepper dust and extracts (raw and dried-processed) Garlic Trial detail, not advice Prolonged workplace exposure · vs Raw versus dried-processed extracts |
All three workers had confirmed asthma and garlic and chili sensitisation. Dry powdered garlic and onion showed stronger IgE binding than the raw plant. Atopy and sensitisation to plant profilins were extra risk factors. Processed garlic and onion powder showed stronger IgE reactivity than raw (Not applicable) Methods, limits and fundingOutcomes: Asthma assessment, specific IgE, immunoblots Limitations: Three workers exposed to high levels of dust (above 10 mg/m3). It shows allergy to dust at work, not to a pinch in a dish. Funding and conflicts: Not stated in the abstract. Read: abstract |
What we do not know yet
- No trial of garlic powder used as a seasoning was found for any health outcome.
- The abstracts do not give trial quality, so the certainty ratings rest on abstracts and agency pages.
- How common garlic allergy is, and safety of seasoning amounts in young children, were not found.
- Heavy metals, mycotoxins and additives in garlic powder, and how much allicin survives drying, were not researched.
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 4
LDL and total cholesterol
Lowered in trials
Blood fats measured in a routine blood test; high LDL is linked to heart disease.
Mixed findingsResults and what it means
Why it was measured
Doctors use cholesterol numbers to judge heart risk.
Statistical vs. clinical meaning
Small average changes in pooled trials; one well-controlled trial found none.
Safety implication
None specific to the measure.
| Study | Result | People | Product |
|---|---|---|---|
| 8 | Garlic powder: total cholesterol -15.83 mg/dL (95% CI -26.64 to -4.63); LDL -8.11 mg/dL (-15.44 to -1.16) | Adults in 22 and 17 randomised trials | Garlic powder supplements |
| 2 | Total cholesterol -10.21 mg/dL (-13.69 to -6.74); LDL -5.90 mg/dL (-10.51 to -1.29); HDL +2.18 mg/dL | 7,137 adults in 108 trials | Garlic supplementation (forms not listed in the abstract) |
| 6 | No significant change in lipids versus placebo after 12 weeks | 50 adults with raised cholesterol | Garlic powder tablets |
Systolic and diastolic blood pressure
Lowered in trials
The pressure of blood in the arteries when the heart beats (systolic) and rests (diastolic).
Low certaintyResults and what it means
Why it was measured
High blood pressure raises the risk of stroke and heart disease.
Statistical vs. clinical meaning
Small average changes, not shown to prevent strokes.
Safety implication
None specific to the measure.
| Study | Result | People | Product |
|---|---|---|---|
| 8 | Garlic powder: systolic -4.34 mmHg (95% CI -8.38 to -0.29); diastolic -2.36 mmHg (-4.56 to -0.15) | Adults in 9 and 10 randomised trials | Garlic powder supplements |
| 2 | Systolic -3.71 mmHg (-5.07 to -2.36); diastolic -1.97 mmHg (-2.86 to -1.08) | 7,137 adults in 108 trials (not all measured pressure) | Garlic supplementation |
Fasting blood glucose
Lowered in trials
The sugar level in the blood after not eating overnight.
Low certaintyResults and what it means
Why it was measured
Used to screen for and follow diabetes.
Statistical vs. clinical meaning
Small, uneven average drops in a lab number; not shown to improve diabetes outcomes.
Safety implication
Possible extra effect with diabetes medicine; ask a clinician.
Number of common colds
Lowered in trials
How many colds a person reports over a period.
Not enough evidenceResults and what it means
Why it was measured
A direct count of the outcome people care about.
Statistical vs. clinical meaning
One trial with self-reported colds; Cochrane calls the evidence insufficient.
Safety implication
Rash and odour were reported.
| Study | Result | People | Product |
|---|---|---|---|
| 9 | 24 colds with garlic versus 65 with placebo (P<0.001) | 146 adults, 12 weeks | Garlic supplement, 180 mg allicin content |
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 5
- The research cautions are about garlic supplements, not a pinch in food. NCCIH says garlic taken by mouth has been used safely in research studies lasting as long as 7 years, but its warnings (bleeding risk, medicine interactions, pregnancy) are about garlic supplements. LactMed says garlic is generally recognized as safe (GRAS) by the FDA as a food flavouring, including during breastfeeding. We found no source that describes harm from garlic powder used to season food in normal amounts, other than allergy. Authoritative guidance 20 19
- Allergy: avoid if you are allergic to garlic or its relatives. LactMed says garlic can cause allergy and should be avoided by people allergic to garlic or to other lily-family plants such as hyacinth, tulip, onion, leek and chives. A case report describes life-threatening anaphylaxis after eating raw garlic, and lab work in that report found the allergens mostly broken down by heating (the authors suggest, but did not test, that cooked garlic may be tolerated). In three spice-mill workers with asthma from spice dust, dry powdered garlic and onion bound more allergy antibody than the raw plant. That was workplace dust, not seasoning. Call emergency services for trouble breathing or swelling of the face or throat. Case report 19 10 25 3
- Bleeding: supplements may add to the effect of blood thinners and aspirin. NCCIH says taking garlic supplements may increase the risk of bleeding and that people having surgery or taking anticoagulants or aspirin should tell their health care providers. LactMed says garlic has anti-platelet effects. In a small crossover trial of 18 healthy volunteers, raw garlic in a dish did not impair platelet function, and the authors judged socially acceptable amounts unlikely to raise bleeding risk around surgery. That trial used raw garlic, not garlic powder or supplements. Authoritative guidance 20 19 14
- Pregnancy: food amounts versus larger amounts. NCCIH says garlic may not be safe in pregnancy or breastfeeding when taken by mouth in amounts greater than those found in foods. LactMed says garlic is GRAS as a food flavouring, including in breastfeeding, and that its odour passes into breast milk. Authoritative guidance 20 19 15
- Raw garlic on the skin can burn. NCCIH warns that fresh raw garlic used on the skin can cause severe irritation and chemical burns. A review found 39 patients with burns, mostly second-degree. This is about putting garlic on the skin, not about seasoning. Case report 20 4
Side effects 5
| Effect | How often | Severity and recovery | Evidence |
|---|---|---|---|
| Breath and body odour The most common and best-documented complaint (review of clinical trials). In the pregnancy trial, women given garlic were more likely to report odour (RR 8.50). | Not established | mild Not stated in the abstract | Authoritative guidance 20 3 11 |
| Stomach pain, wind and nausea (by mouth) Listed by NCCIH for oral garlic; no frequency given. | Not established | mild Not stated | Authoritative guidance 20 |
| Allergic reactions including anaphylaxis Case reports describe hives, angioedema, contact dermatitis and anaphylaxis. No source read says how common garlic allergy is. | Not established | can be severe Not stated | Case report 10 3 19 |
| Skin burns from raw garlic on the skin Fresh garlic on skin or mucous membranes, not eating it. | 39 patients in 32 articles | second-degree burns in most Treated mainly with symptom care | Case report 4 20 |
| Possible bleeding tendency (supplements) NCCIH: garlic supplements may increase bleeding risk. Case reports in the review note altered platelet function and coagulation. | Not established | not stated Not stated | Authoritative guidance 20 3 |
Liver
No liver injury from garlic powder as a seasoning was found in the sources read. A liver-safety source (such as LiverTox) was not searched for this page.
How often. No frequency was found.
Monitoring. No agency monitoring advice was found.
This is a safety connection. It is not evidence that Garlic powder supports liver health.
Medicines and supplements 4
| With | Why it matters | Importance | Evidence | What to do |
|---|---|---|---|---|
| Blood thinners (anticoagulants) and aspirin prescription | Garlic has anti-platelet effects (LactMed) and supplements may increase bleeding risk (NCCIH). | NCCIH advises asking your provider before using garlic if you take an anticoagulant, aspirin or any other medicine. The sources read do not describe a problem with a seasoning pinch. | Authoritative guidance Moderate certainty 20 19 3 | Tell your care team about garlic supplements, especially before surgery. |
| Warfarin prescription | A review says garlic may enhance anticoagulants such as warfarin. A crossover trial in 12 healthy men found garlic pre-treatment for 2 weeks did not significantly change warfarin levels or its effect after a single warfarin dose. | Mixed. Case-report-based reviews suggest a possible effect; the one trial read was null in healthy men on a single dose. It does not show safety in people on long-term warfarin. | Controlled trial Mixed findings 12 3 | Ask your warfarin clinic about garlic supplements. |
| Saquinavir (HIV medicine) prescription | Garlic caplets lowered saquinavir levels in 10 healthy volunteers: AUC fell 51%, trough 49% and Cmax 54%. | The authors advise caution when garlic supplements are combined with saquinavir used as the only protease inhibitor. Garlic supplements were tested, not food. | Controlled trial Low certainty 13 3 | Ask your HIV clinician or pharmacist before using garlic supplements. |
| Other medicines prescription | NCCIH says some herbs and medicines interact in harmful ways. | The sources read name no other specific medicines for garlic as a seasoning. | Authoritative guidance Not enough evidence 20 | Ask a doctor or pharmacist about garlic supplements if you take any medicine. |
Who should check first 5
| Situation | Advice | Evidence |
|---|---|---|
| Known allergy to garlic, onion, leek, chives, hyacinth or tulip | LactMed says avoid garlic. Ask an allergist. | Authoritative guidance 19 |
| Taking anticoagulants or aspirin, or having surgery (garlic supplements) | Tell your providers about garlic supplements. The sources read describe no problem with a seasoning pinch. | Authoritative guidance 20 |
| Pregnancy and breastfeeding | NCCIH: garlic by mouth in amounts greater than in food may not be safe. LactMed: GRAS as a food flavouring, including during breastfeeding. Ask your midwife or doctor about supplements. | Authoritative guidance 20 19 |
| Babies and young children | The sources read give no food guidance for children. LactMed urges caution with garlic on the skin of infants. | Authoritative guidance 19 |
| Taking saquinavir | Ask your clinician before using garlic supplements. | Controlled trial 13 |
Overdose, product quality and regulators
Summary. No toxicity from garlic powder used as a seasoning was found in the sources read. The documented harms are allergy, skin burns from raw garlic on skin, and bleeding or medicine concerns with supplements.
Animal. Not reviewed.
Human doses studied. Trial amounts are trial details, not advice. NCCIH says oral garlic has been used safely in research studies lasting as long as 7 years.
High dose or long term signals. Bleeding signals with supplements (NCCIH). No source read describes harm from normal food use other than allergy.
Overdose response. Not found.
Genotoxicity. Not researched.
Dried spices can carry germs: a 2020 lab paper says Salmonella has caused many outbreaks related to spice consumption, and it developed a way to detect Salmonella in garlic powder and other dried spices. It does not say how common contamination of garlic powder is. Heavy metals, mycotoxins and pesticides in garlic powder were not researched.
Salmonella in dried spices. The abstract says Salmonella is the cause of many outbreaks related to spice consumption and that spices' own antimicrobial properties make detection hard. Garlic powder was one of the spice samples used in the lab method. 1
Garlic salt and added ingredients. Garlic salt is a different product from garlic powder. Plain garlic powder has about 60 mg sodium per 100 g (about 2 mg per teaspoon) by USDA data; check the label of seasoning blends if you limit salt. 24
| Body | Action | Date |
|---|---|---|
| NCCIH (US National Institutes of Health) (United States) | Garlic page: supplements may modestly lower cholesterol, may increase bleeding risk; oral garlic may not be safe in pregnancy or breastfeeding in amounts greater than in food; raw garlic on skin can burn source | 2025-02-01 |
| LactMed (US National Library of Medicine), citing the FDA (United States) | Garlic is generally recognized as safe (GRAS) as a food flavouring by the FDA, including during lactation; avoid if allergic; anti-platelet effects; caution with garlic on skin source | 2026-05-15 |
When to get medical help
- Trouble breathing, swelling of the lips, face or throat, or widespread hives after eating garlic
- Signs of serious bleeding while taking a blood thinner and garlic supplements, such as blood in urine or stool or unexplained bruising
- A blistering or burning skin reaction after garlic was put on the skin
- Vomiting, diarrhoea, stomach pain or fever after eating a contaminated food
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 is garlic powder good for?
Does garlic powder lower cholesterol?
Does garlic powder lower blood pressure?
Is garlic powder as good as fresh garlic?
Is garlic powder safe with blood thinners?
Should I stop garlic before surgery?
NCCIH says garlic supplements may increase bleeding risk and to tell your providers, especially before surgery. Ask your surgeon about both supplements and food.
Is garlic powder safe in pregnancy or breastfeeding?
Can you be allergic to garlic powder?
Does garlic powder cause bad breath?
Does garlic powder prevent colds or cancer?
Is garlic salt the same as garlic powder?
No. Garlic salt is a different product with added salt. Plain garlic powder has about 60 mg sodium per 100 g by USDA data, about 2 mg per teaspoon. Check labels of blends if you limit salt.
Can dried spices carry germs?
Yes. A 2020 lab paper says Salmonella has caused many outbreaks related to spice consumption. It does not say how often garlic powder is affected.
Explore by health goal
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 started from our existing garlic powder summary, re-checked nutrition against USDA FoodData Central data, read the NCCIH and LactMed pages and searched PubMed for reviews, trials and case reports. Only abstracts were read for studies. Items we could not verify are flagged in the research gaps.
- 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.
Sources 25
Each source was opened and checked. Where we read only the abstract, it says so. The small numbers in the text point here.
- Barrere V, Tompkins E, Armstrong M, et al.. Optimization of Salmonella detection in garlic, onion, cinnamon, red chili pepper powders and green tea. International Journal of Food Microbiology. 2020. PMID 31733520. DOI 10.1016/j.ijfoodmicro.2019.108440. (abstract)
- Behrouz V, Zahroodi M, Clark CCT, et al.. Effects of Garlic Supplementation on Cardiovascular Risk Factors in Adults: A Comprehensive Updated Systematic Review and Meta-Analysis of Randomized Controlled Trials. Nutrition Reviews. 2026. PMID 40580481. DOI 10.1093/nutrit/nuaf090. (abstract)
- Borrelli F, Capasso R, Izzo AA. Garlic (Allium sativum L.): adverse effects and drug interactions in humans. Molecular Nutrition and Food Research. 2007. PMID 17918162. DOI 10.1002/mnfr.200700072. (abstract)
- Hitl M, Kladar N, Gavaric N, et al.. Garlic burn injuries - a systematic review of reported cases. American Journal of Emergency Medicine. 2021. PMID 33571752. DOI 10.1016/j.ajem.2021.01.039. (abstract)
- Hou LQ, Liu YH, Zhang YY. Garlic intake lowers fasting blood glucose: meta-analysis of randomized controlled trials. Asia Pacific Journal of Clinical Nutrition. 2015. PMID 26693740. DOI 10.6133/apjcn.2015.24.4.15. (abstract)
- Isaacsohn JL, Moser M, Stein EA, et al.. Garlic powder and plasma lipids and lipoproteins: a multicenter, randomized, placebo-controlled trial. Archives of Internal Medicine. 1998. PMID 9625398. DOI 10.1001/archinte.158.11.1189. (abstract)
- Kodali RT, Eslick GD. Meta-analysis: Does garlic intake reduce risk of gastric cancer?. Nutrition and Cancer. 2015. PMID 25411831. DOI 10.1080/01635581.2015.967873. (abstract)
- Kwak JS, Kim JY, Paek JE, et al.. Garlic powder intake and cardiovascular risk factors: a meta-analysis of randomized controlled clinical trials. Nutrition Research and Practice. 2014. PMID 25489404. DOI 10.4162/nrp.2014.8.6.644. (abstract)
- Lissiman E, Bhasale AL, Cohen M. Garlic for the common cold. Cochrane Database of Systematic Reviews. 2014. PMID 25386977. DOI 10.1002/14651858.CD006206.pub4. (abstract)
- Ma S, Yin J. Anaphylaxis induced by ingestion of raw garlic. Foodborne Pathogens and Disease. 2012. PMID 22817136. DOI 10.1089/fpd.2012.1133. (abstract)
- Meher S, Duley L. Garlic for preventing pre-eclampsia and its complications. Cochrane Database of Systematic Reviews. 2006. PMID 16856110. DOI 10.1002/14651858.CD006065. (abstract)
- Mohammed Abdul MI, Jiang X, Williams KM, et al.. Pharmacodynamic interaction of warfarin with cranberry but not with garlic in healthy subjects. British Journal of Pharmacology. 2008. PMID 18516070. DOI 10.1038/bjp.2008.210. (abstract)
- Piscitelli SC, Burstein AH, Welden N, et al.. The effect of garlic supplements on the pharmacokinetics of saquinavir. Clinical Infectious Diseases. 2002. PMID 11740713. DOI 10.1086/324351. (abstract)
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Where to buy
Check the label first. Whatever you buy, look for these:
- Whole or ground: whole spices keep their flavor longer
- The origin and a packed-on or best-by date for freshness
- Organic or non-irradiated labeling if that matters to you
- A resealable, airtight container
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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