Medication classCommon adverse effectsSubstances that increase concentration (not fully inclusive)*Substances that decrease concentration*

  • Calcineurin inhibitors (e.g., cyclosporine [Sandimmune], tacrolimus [Prograf])

  • Hyperkalemia, hypertension, nephrotoxicity, neurotoxicity (e.g., headaches, tremors, neuropathy, seizures)

  • Cyclosporine: dyslipidemia, gingival hyperplasia

  • Tacrolimus: diabetes mellitus

  • Aminoglycosides

  • Amphotericin B

  • Antifungals: fluconazole (Diflucan), itraconazole (Sporanox), ketoconazole

  • Cardiac medications: amiodarone

  • Contraceptives: ethinyl estradiol

  • Diuretics: spironolactone (hyperkalemia)

  • Fluoroquinolones (primarily ofloxacin; ciprofloxacin and levofloxacin [Levaquin] often used safely)

  • Grapefruit and grapefruit juice

  • Macrolides (erythromycin more than clarithromycin [Biaxin])

  • Metronidazole (Flagyl)

  • Nondihydropyridine calcium channel blockers: diltiazem, verapamil

  • Nonsteroidal anti-inflammatory drugs (can increase nephrotoxicity)

  • Pineapple and papaya (inhibit cyclosporine metabolism)

  • Pomegranates and pomegranate juice

  • Warfarin (Coumadin)

  • Antacids

  • Antibiotics: nafcillin, rifampin

  • Anticonvulsants: carbamazepine (Tegretol), phenytoin (Dilantin)

  • Cholestyramine (Questran)

  • Loperamide (Imodium)

  • Supplements: echinacea (may cause organ rejection), St. John's wort

  • Valproic acid (Depakene)

  • Mammalian target of rapamycin inhibitors (e.g., sirolimus, everolimus)

  • Dyslipidemia, hepatic artery thrombosis, myelosuppression, poor wound healing, pulmonary fibrosis, rash, ulcerations

  • Ciprofloxacin

  • Linezolid (Zyvox; increased myelosuppression)

  • Macrolides (erythromycin more than clarithromycin)

  • Rifampin

  • Purine synthesis inhibitors (e.g., azathioprine [Imuran], mycophenolate [Cellcept], mycophenolic acid [Myfortic])

  • Azathioprine: cholestatic hepatitis

  • Mycophenolate/mycophenolic acid: bone marrow suppression, gastrointestinal issues (e.g., abdominal pain, diarrhea, gastritis, nausea)

  • Linezolid

  • Valganciclovir (Valcyte; increased myelosuppression)

  • Allopurinol can increase levels to toxic levels (especially azathioprine)

  • Rifampin