The active ingredient in ENVARSUS XR is tacrolimus. ENVARSUS XR and other forms of tacrolimus have many drug-drug interactions. Some of these interactions can be toxic, and some can decrease the drug levels until it is ineffective, which can cause organ rejection. Never start, stop, or change the drugs you are taking without talking with your doctor and pharmacist first. Alcohol, Amiodarone, Anticonvulsants, Azole antifungals, Boceprevir, Carbamazepine, Chloramphenicol, Cimetidine, Clarithromycin, Diltiazem, Ethinyl Estradiol, Danazol, Lansoprazole, Magnesium and aluminum antacids, Methylprednisolone, Metoclopramide, Mycophenolic acid, Nefazodone, Nelfinavir, Nicardipine, Nifedipine, Omeprazole, Phenobarbital, Prednisone, Rifabutin, Rifampin, Ritonavir, St. John's Wort, Telaprevir, Troleandomycin, Verapamil
