Administration: Take with foodMost common side effects: Diarrhea, nausea, headacheDrug interactions: Screen for drug interactions†Contraindications: Inhibits CYP3A enzyme resulting in many contraindications with medications; drug interaction review is criticalCautions: Risk for Stevens-Johnson syndrome and toxic epidermal necrosis; can cause hepatotoxicity; use with caution in persons with a sulfonamide allergy; cobicistat increases serum creatinine without affecting glomerular filtration rate. The gene discussed is CYP3A4; the disease is Stevens-Johnson syndrome.