Allium
Scientific Name: Garlic
Other Names: Allium sativum, Rustic Treacle, Stinking Rose
What interactions should I watch for?
Prescription Drugs
In studies and case reports, garlic has been shown to increase the time blood needs to clot. When it is taken with "blood thinners"--antiplatelet or anticoagulant drugs, the effect of the drug may be increased, resulting in uncontrolled bleeding.
- Antiplatelet drugs include clopidogrel and Ticlid
- Anticoagulants include heparin and warfarin
When garlic was given to healthy volunteers who were also taking a type of antiviral drug (a protease inhibitor named Fortovase); blood levels of the drug were reduced by about half, making it less effective for controlling HIV. Although garlic's possible effects on other antiviral drugs are unknown, individuals taking any type of antiviral therapy should avoid taking very large amounts of garlic.
A few small studies seem to show that garlic can reduce blood sugar in laboratory animals. Although additional studies are needed to document these results, individuals taking oral medications or insulin for diabetes should check with their doctors before taking large amounts of garlic.
Because garlic is broken down by certain enzymes in the liver, excessively large amounts of it possibly may interfere with the use of prescription drugs that are processed by the same enzymes. Some of these drugs are:
- Allergy drugs such as fexofenadine
- Antifungal drugs such as itraconazole and ketoconazole
- Cancer drugs such as etoposide, paclitaxel, vinblastine, or vincristine
- Drugs for high cholesterol such as lovastatin, pravastatin, and simvastatin
- Oral contraceptives
Non-prescription Drugs
Garlic can reduce the ability of blood to clot after an injury. Aspirin can also decrease clotting, so large amounts of garlic should not be taken orally at the same time aspirin is being taken.
Both garlic and acetaminophen are processed by the same set of enzymes in the liver. When they are taken together, large amounts of garlic may interfere with the breakdown of acetaminophen. As a result too much acetaminophen may stay in the blood. In rare cases, very high blood levels of acetaminophen can cause liver damage.
Herbals
Theoretically, if garlic is used with other herbs that affect blood clotting, excessive bleeding is possible. Some of the most common herbal products that might inhibit blood clotting are:
- Danshen
- Devil's Claw
- Eleuthero
- Ginger
- Gingko
- Horse Chestnut
- Panax Ginseng
- Papain
- Red Clover
Some interactions between herbal products and medications can be more severe than others. The best way for you to avoid harmful interactions is to tell your doctor and/or pharmacist what medications you are currently taking, including any over-the-counter products, vitamins, and herbals. For specific information on how garlic interacts with drugs, other herbals, and foods and the severity of those interactions, please use our Drug Interactions Checker to check for possible interactions.
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What interactions should I watch for?
