Garlic

Also known as allium sativum, garlic extract, alicin, allicin.

Last reviewed October 9, 2026 · Jump to references

What is Garlic?

In plain words

Garlic is a plant used as a food and made into extracts and supplements. Crushing it produces allicin, a sulfur-containing substance that quickly changes into other compounds as it is processed and digested. Researchers study garlic for possible effects on blood pressure and cholesterol, but findings vary across products and studies. Garlic supplements can increase bleeding risk, especially when combined with blood-thinning medicines.

Technical definition

Garlic (Allium sativum) is a botanical whose bulbs contain organosulfur compounds, including alliin, which the enzyme alliinase converts to allicin when the tissue is crushed or cut. Allicin is unstable and forms additional sulfur compounds; these constituents act through multiple biochemical pathways rather than a single receptor, with research examining effects on vascular signaling, platelet function, and lipid metabolism. In the United States, garlic is sold as a food and dietary supplement; supplements are not FDA-approved treatments for disease.

Educational information only. This page does not provide medical advice or determine whether a supplement is appropriate for you. Review supplements with a qualified healthcare professional, especially if you take medication, are pregnant, have surgery scheduled, or have a chronic medical condition.

Important cautions

Bleeding considerationsmoderate concern
Garlic supplements can reduce platelet aggregation and may add to anticoagulant and antiplatelet medicines. Review with a clinician if you take these or have a bleeding disorder.
Disclose before surgerymoderate concern
Tell surgical and dental teams about garlic supplements so bleeding risk and timing can be assessed.
May reduce levels of some medicinesmoderate concern
Garlic has been reported to lower blood levels of saquinavir and may affect other medicines; check with a pharmacist.

Discuss with a clinician if any of these apply

Bleeding disorders or anticoagulants
Upcoming surgery

Evidence by use

Each use is rated on its own. There is no single overall effectiveness score.