Garlic offers a lot of beneficial effects to health, but it may alter the function of certain prescription medications. This is why we should not take garlic supplements without first talking to a health care provider if we are under medication.

For example, garlic may exaggerate the activity of medications that inhibit the action of platelets in the body. Examples of such medications include indomethacin, dipyridamole, plavix, and aspirin.

There have been reports of a possible interaction between garlic and warfarin that could increase the risk of bleeding in people taking this blood thinning medication. Therefore, when taking medications that may thin the blood, such as aspirin and warfarin, you not use garlic supplements unless you are under the supervision of a doctor.

Garlic may also reduce blood levels of protease inhibitors, a medication used to treat people with the human immunodeficiency virus (HIV). Protease inhibitors include indinavir, ritinavir, and saquinavir.