Skip main navigation



What is garlic used for and are there any side effects?


Garlic is the bulb of a tall, flowering plant and is used in cooking throughout the world. Some people believe that eating garlic can reduce cholesterol and lower blood pressure. Some claim that garlic can also cure bacterial, fungal and viral infections. Some even claim that garlic can prevent aging and cancer.

Medical research on garlic focusing on its ability to reduce cholesterol and blood pressure is inconclusive. For example, early studies showed that a daily dose (garlic has a wide range of doses) of 600 to 900 mg of garlic powder reduced blood levels of cholesterol after 12 weeks. But more recent studies show that garlic may be less effective at lowering cholesterol or blood pressure.

Garlic side effects

Garlic very rarely has side effects attached to its use, and if there are side effects, they are typically very minor. Common minor side effects include gas, heartburn, body odor, nausea, sweating, lightheadedness, burning of esophagus, mouth, or stomach, asthma, and bad breath. These effects are more common with higher doses. Topical exposure has led to contact dermatitis (allergic skin reaction). In rare cases, anaphylaxis has occurred.

Drug interactions

There is the potential for some drug interactions with garlic and garlic supplements. Garlic may increase the possibility of bleeding in people who are taking anticoagulants or "blood thinners" such as warfarin (Coumadin®), clopidogrel (Plavix®), indomethacin (Indocin®), or aspirin. Please check with your doctor before starting garlic if you are currently using a blood thinner.

There are other possible drug interactions beyond interactions with blood thinners. Large doses of garlic can reduce levels of the protease inhibitor Invirase®. Garlic may also affect other HIV medications such as Crixivan®, Norvir®, Rescriptor® and Viramune®. If you are taking any HIV medications you should not take garlic supplements. Currently, there is no proof that garlic is helpful in HIV infections and garlic supplements may decrease the effectiveness of your HIV therapy.

Back to Ask a Pharmacist


Answers to questions regarding information about medications or health conditions are not for diagnostic or treatment purposes and are not conclusive as to the presence or absence of any health condition. Consult your physician for diagnosis and treatment of your medical condition. The information provided is not a substitute for medical advice. Advances in medicine may cause this information to become outdated, invalid or subject to debate. Professional opinions and interpretations of the scientific literature may vary. Walgreens' terms of use and general warranty disclaimer apply to all services provided. If you are in need of immediate medical attention, contact your physician, poison control center or emergency medical professional. If you need to speak with a pharmacist for non-emergency matters, contact your local Walgreens pharmacist or call a pharmacist toll-free at 1 (877) 250-5823.

Your Digital Health Advisor. Powered by WebMD. Manage diabetes with this easy online tool.* Get started.
Your Digital Health Advisor. Powered by WebMD. Manage diabetes with this easy online tool.* Get started.

Balance Rewards for Healthy Choices

20 Points
20 Points

Now you can track your blood pressure and blood glucose.

Start earning points Go Arrow