Coadministration of famotidine (40 mg once daily given 12 hours after elvitegravir) and elvitegravir/cobicistat (150/150 mg once daily) increased elvitegravir Cmax, AUC and Cmin by 2%, 3% and 18% respectively (n=10). When the same doses were given simultaneously, there was no change in elvitegravir Cmax, but AUC and Cmin increased by 3% and 7% (n=16). No dose adjustment is needed when Stribild is combined with H2 receptor antagonists. Emtricitabine and tenofovir-DF do not interact with famotidine.