Researchers have found garlic supplements can cause harmful side effect when combined with a type of medication used to treat AIDS. Garlic supplements reduced blood levels of the saquinavir, one of a class of drugs called protease inhibitors that are effective at slowing the progression of HIV infection. In the presence of garlic supplements, blood concentrations of saquinavir decreased by about 50 percent.
For the study, nine healthy, HIV-negative volunteers received saquinavir. The research team drew samples from the volunteers' blood to measure their baseline levels of saquinavir in the bloodstream. Next, the volunteers took garlic caplets twice daily for three weeks. When the researchers again analyzed blood samples, the average overall levels of saquinavir had decreased 50 percent.
The clear implication is that doctors and patients should be cautious about using garlic supplements during HIV therapy.