Side Effects of Garlic Capsules

Garlic has been used as a flavoring and a medicine for thousands of years. It was munched by Egyptians during the time of the pharaohs and by gravediggers during the time of the Black Plague. More recently, garlic's extremely high antioxidants have led to multiple studies of its efficacy as a remedy for heart disease, high blood pressure, cancer, parasites and the common cold. Lab studies usually involve aged garlic extract and dried garlic capsules. The University of Maryland Medical Center says garlic has very low toxicity but may cause some side effects.

Uncommon Side Effects

• Aside from rather powerful breath, garlic seldom has a negative effect on the body. In some people, however, it has been known to cause fatigue, headache, vertigo or dizziness, skin rashes and asthmatic reactions. Garlic pill poppers might experience loss of appetite and muscle aches. The herb and the capsules can contribute to an upset stomach or a feeling of bloating, to heartburn, flatulence and diarrhea.

Pre-Surgery Precautions

• Garlic is a blood-thinner. It can increase the risk of bleeding during surgery or delivery of a baby. The Linus Pauling Institute reports that garlic may increase the effects of wayfarin, a blood-thinner. If you take wayfarin or aspirin, consult your doctor before adding garlic supplements to your diet.

Fish Oil and Garlic

• Garlic is very tasty when cooked with fish, but garlic extracts may not be the perfect choice to consume with fish oils. Garlic has antiplatelet properties that enhance medications and supplements that block platelets from clumping. Some medications that may not mix well with garlic are indomethacin, dipyridamole, Plavix and other anticoagulants like high-dose fish oil and vitamin E.

Garlic and Anti-HIV Drugs

• Garlic might decrease the levels of protease inhibitors in the blood according to the University of Maryland Medical Center. Protease inhibitors prevent viruses like HIV from replicating and have been shown to be effective at reducing or eliminating traces of virus from the blood. Garlic should be taken only under a doctor's supervision if you are prescribed indinavir, ritonavir, saquinavir or another protease inhibitor.