Coadministration has not been studied and is not recommended in the product labels for Descovy. St John’s wort, a P-gp inducer, may decrease tenofovir alafenamide plasma concentrations. However, a recent study suggests a low risk of a clinically relevant pharmacokinetic interaction with low-hyperforin formulations (<1 mg/day) of St John’s Wort (hyperforin is the constituent responsible for induction of CYPs and P-gp). Coadministration may be considered with St John’s Wort formulations that clearly state the hyperforin content and which have a total daily hyperforin dose of 1 mg or less. In addition, data from a study with rifampicin suggest that use of tenofovir alafenamide 25 mg once daily with primidone may be acceptable. Coadministration of emtricitabine/tenofovir alafenamide (200/25 mg once daily) and the strong inducer rifampicin (600 mg once daily) decreased plasma exposure of tenofovir alafenamide and tenofovir by ~55%. Intracellular tenofovir-DP AUC decreased by 36%, however, intracellular tenofovir-DP exposure was 4.2-fold higher than that achieved with standard dose tenofovir-DF alone (300 mg once daily). No interaction is expected with emtricitabine.