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Garlic
Garlic — what the European monograph actually supports, what it is not for, the form and how long it is meant to be used, side effects, and the 3 medicine interactions documented for it.
This is a reference page, not a diagnosis and not a prescription. Herbal products are real pharmacology: they have effects, side effects and interactions with medicines. Tell your doctor and your pharmacist everything you take, including teas and supplements, and never stop or change a prescribed medicine because of anything you read here.
What it is
Allium sativum L. — bulb (Allii sativi bulbus)
Local names across the region this site serves: küüslauk (ET) · valkosipuli (FI) · чеснок (RU).
Grouped here under Kitchen spices with a safety story. Regulatory position: EU herbal monograph — traditional use; the indications concern mild circulatory complaints.
What the evidence supports
The registered indication: Relief of symptoms of mild circulatory complaints, in traditional-use preparations. Not the treatment of cardiovascular disease.
Garlic's medicinal reputation rests on allicin, which does not exist in an intact clove: it forms when alliin meets the enzyme alliinase as the clove is crushed or chopped, and it is unstable from that moment. This single fact explains why aged garlic extract, garlic oil macerate, dried powder and enteric-coated tablets all contain different compounds and cannot be compared with one another or with a clove in a pan. On the outcomes people buy it for — cholesterol and blood pressure — reviews find at most modest effects, inconsistent across preparations, and nothing that substitutes for treatment where treatment is indicated. What is clinically solid is the other side: garlic inhibits platelet aggregation, which is why it sits on surgical stop-before-your-operation lists.
C — Traditional use only Plausible from thirty or more years of use, which is what a traditional-use registration means. No clinical evidence was required and none has settled it.
What it is not for
High cholesterol or high blood pressure as a replacement for treatment, and infections. Raw garlic applied to skin as a folk remedy for warts or infections causes chemical burns — this is a documented and entirely avoidable injury.
Form, strength and how long
Fresh and cooked cloves as food, dried powder tablets, aged garlic extract, oil macerates and enteric-coated preparations. Odour-free products have usually removed the compounds responsible for the effects as well as the smell.
Duration. Culinary use is food. Supplement courses should be paused before planned surgery.
No gram figure appears on this page on purpose. The plant part, the extraction solvent and the drug-to-extract ratio together define a preparation, and a number taken from one does not describe another. The reasoning is set out on the hub; the amount that applies to you is the one printed on the pack you are holding, and a pharmacist will read it with you.
Side effects
Breath and body odour, heartburn, stomach upset and wind. Contact dermatitis in people who handle raw garlic regularly, such as cooks. Chemical burns from raw garlic applied to skin.
Who should avoid it
Culinary amounts are fine in pregnancy. Supplement amounts are not established. Stop supplements before surgery.
Interactions with medicines
| Medicine or substance | What is described |
|---|---|
| Anticoagulants and antiplatelets (warfarin, DOACs, aspirin, clopidogrel) | Antiplatelet activity adds to warfarin, DOACs, aspirin and clopidogrel. Case reports of bleeding exist. Supplement amounts matter far more than what goes in the pan. |
| HIV and hepatitis C antivirals | A documented interaction with the HIV medicine saquinavir, in which garlic supplements substantially reduced its blood level, is why garlic supplements are flagged specifically in HIV care. |
| Planned surgery and anaesthesia | Stop garlic supplements before planned surgery and tell the surgical team you have been taking them. |
The reverse view — start from the medicine rather than the plant — is in the medicine, food and alcohol interactions reference, and summarised for every herb on this site.
As a food
This one is also in the kitchen, so the nutrition figures are worth having next to the pharmacology: see the food data page for calories and nutrients per 100 g and per portion. Culinary amounts and medicinal preparations are different exposures, and the difference is usually the whole safety story.
Sources: European Medicines Agency — Committee on Herbal Medicinal Products (HMPC), European Union herbal monographs · NIH National Center for Complementary and Integrative Health — herb fact sheets · checked 2026-09-06
Frequently asked questions
What is garlic used for?
Relief of symptoms of mild circulatory complaints, in traditional-use preparations. Not the treatment of cardiovascular disease. Garlic's medicinal reputation rests on allicin, which does not exist in an intact clove: it forms when alliin meets the enzyme alliinase as the clove is crushed or chopped, and it is unstable from that moment. This single fact explains why aged garlic extract, garlic oil macerate, dried powder and enteric-coated tablets all contain different compounds and cannot be compared with one another or with a clove in a pan. On the outcomes people buy it for — cholesterol and blood pressure — reviews find at most modest effects, inconsistent across preparations, and nothing that substitutes for treatment where treatment is indicated. What is clinically solid is the other side: garlic inhibits platelet aggregation, which is why it sits on surgical stop-before-your-operation lists.
Does garlic work?
Graded C here: Plausible from thirty or more years of use, which is what a traditional-use registration means. No clinical evidence was required and none has settled it. High cholesterol or high blood pressure as a replacement for treatment, and infections. Raw garlic applied to skin as a folk remedy for warts or infections causes chemical burns — this is a documented and entirely avoidable injury.
How much garlic should I take?
This reference does not print gram figures, because they do not transfer between preparations of different extract strength. What can be said honestly is the form and the duration: Fresh and cooked cloves as food, dried powder tablets, aged garlic extract, oil macerates and enteric-coated preparations. Odour-free products have usually removed the compounds responsible for the effects as well as the smell. Culinary use is food. Supplement courses should be paused before planned surgery.
What are the side effects of garlic?
Breath and body odour, heartburn, stomach upset and wind. Contact dermatitis in people who handle raw garlic regularly, such as cooks. Chemical burns from raw garlic applied to skin.
Does garlic interact with medicines?
Yes — documented for Anticoagulants, warfarin, HIV medicines, Surgery. Each one is described on this page, with a link to the medicine-side reference where one exists.
Others in kitchen spices with a safety story
Cinnamon
Nothing that survives a systematic review. It is a spice with a real safety figure attached.
Nutmeg
Nothing medicinal. It is on this list because it is the kitchen spice that poisons people.
Green tea extract
Marketed for weight loss and metabolism. Neither claim survives review.
Chilli and cayenne (capsaicin)
Topical relief of muscle and joint pain in low-strength preparations; high-concentration capsaicin patches are licensed medicines for peripheral neuropathic pain.
Keep the whole list in one place
TempoLife logs supplements alongside food, sleep and how you actually felt — so the answer to "what are you taking?" is a screen, not a guess.