Norvir should not be used as an antiviral medicine by patients taking any of the following medicines: • alfuzosin (used to treat benign prostatic hyperplasia [BPH, enlarged prostate gland]); • meperidine, piroxicam, propoxyphene (used to relieve pain); • amiodarone, bepridil, encainide, flecainide, propafenone, quinidine (used to correct irregular heartbeat); • fusidic acid, voriconazole (at ritonavir doses of 400 mg twice a day or more), rifabutin (used to treat infections); • astemizole, terfenadine (commonly used to treat allergy symptoms - these medicines may be available without a prescription); • clozapine, pimozide (used to treat mental illness); • dihydroergotamine, ergonovine, ergotamine, methylergonovine (used to treat migraine headache); • cisapride (used to relieve certain stomach problems); • lovastatin, simvastatin (used to lower cholesterol in the blood); • clorazepate, diazepam, estazolam, flurazepam, midazolam (when taken by mouth), triazolam (used to relieve anxiety or difficulty sleeping); • St John’ s wort (a herbal preparation used to treat depression).