Interactions between complementary medicines and drugs used in primary care and oral COVID-19 antiviral drugs

Abstract

Background Patient harm resulting from drug interactions between conventional and traditional or complementary medicines (CM) are avoidable. Objective To provide a clinical overview of a selection of CM interactions with drugs commonly used in Australian general practice or in the management of COVID-19. Discussion Many herb constituents are substrates for cytochrome P450 enzymes, and inducers and/or inhibitors of transporters such as P-glycoprotein. Hypericum perforatum (St John’s Wort), Hydrastis canadensis (golden seal), Ginkgo biloba (ginkgo) and Allium sativum (garlic) are reported to interact with many drugs. Simultaneous administration of certain anti-viral drugs with zinc compounds and several herbs should also be avoided. Preventing and identifying unwanted CM–drug interactions in primary care requires vigilance, access to CM–drug interaction checkers and excellent communication skills. Potential risks from interactions should be balanced against the potential benefits of continuing the drug and/or CM and involve shared decision making.