Coadministration with sofosbuvir is not recommended. St John's wort is a potent inducer of P-gp and may significantly decrease sofosbuvir concentrations. This may result in loss of efficacy and potential virological failure. However, the constituent of St John’s Wort responsible for induction of enzymes and transporters, hyperforin, can be highly variable between extracts. 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. 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.