Coadministration has not been studied and is not recommended as it may decrease rilpivirine concentrations. Combining two NNRTIs has not been shown to be beneficial. Furthermore, rilpivirine has been associated with prolongation of the QTc interval at supra-therapeutic doses but these are unlikely to occur during coadministration with efavirenz. However, the product labels for rilpivirine indicate that rilpivirine should be used with caution in combination with drugs with a known risk of Torsade de Pointes. Efavirenz has a possible risk of QTc prolongation and/or TdP on the CredibleMeds.org website.