Dietary supplement interactions with antiretrovirals: a systematic review

Many patients who take antiretroviral drugs also take alternative therapies including dietary supplements. Some drug–supplement combinations may result in clinically meaningful interactions. We aimed to investigate the evidence for dietary supplement interactions with antiretrovirals. A systematic review was conducted using multiple resources including PubMed, Natural Medicine Comprehensive Database, The Review of Natural Products, and Google Scholar. All human studies or case reports evaluating an interaction between a dietary supplement and an antiretroviral were selected for inclusion. Twenty-eight pharmacokinetic studies and case-series/case reports were selected for inclusion. Calcium carbonate, ferrous fumarate, some forms of ginkgo, some forms of garlic, some forms of milk thistle, St. John's wort, vitamin C, zinc sulfate, and multivitamins were all found to significantly decrease the levels of selected antiretrovirals and should be avoided in patients taking these antiretrovirals. Cat's claw and evening primrose oil were found to significantly increase the levels of antiretrovirals and patients should be monitored for adverse effects while taking these dietary supplements with antiretrovirals. This systematic review shows the importance of screening all human immunodeficiency virus patients for dietary supplement use to prevent treatment failure or adverse effects related to an interaction.