There are over 180 drug interactions with garlic, but most are reported as minor. Garlic supplements are sold over-the-counter, usually in tablet or capsule form.

• Garlic has been rarely reported to affect blood clotting and may affect people who take blood thinning agents like aspirin, warfarin, clopidogrel (Plavix) or other antocoagulants.
• Use of garlic supplements with HIV protease inhibitors, for example: saquinavir (Invirase) or ritonavir (Norvir), may decrease the protease inhibitor blood levels. Using these medications together can make the HIV medicine less effective. You may need a dose adjustment or special tests to safely take both medications.
• It is important to tell your doctor about all the medications you use, including prescription, over-the-counter (OTC) medicines, vitamins and herbs. Do not stop using any medications without first talking to your doctor.

Garlic is a commonly used flavoring agent, food product and herbal supplement. There are many conditions garlic has been promoted for: to reduce cholesterol and triglycerides, to prevent cancer, to lower blood sugar levels, and to reduce menstrual pain, among other uses.

There are many other possible garlic supplement interactions, so be sure to review all possible drug interactions with garlic and speak with your healthcare provider.

Learn more: Drug interactions with garlic (in more detail)