Contrast-induced nephropathy resulting in metformin accumulation w/ iodinated contrast agents. May require frequent blood glucose & kidney function tests or dose adjustment when co-administered w/ diuretics (eg, furosemide); NSAIDs & COX-2 inhibitors (eg, ibuprofen, celecoxib); ACE inhibitors & angiotensin II receptor antagonists; steroids eg, prednisolone, mometasone, beclomethasone; sympathomimetic medicines eg, epinephrine & dopamine; medicines that may affect metformin blood levels (eg, verapamil, rifampicin, cimetidine, dolutegravir, ranolazine, trimethoprim, vandetanib, isavuconazole, crizotinib, olaparib). Increased risk of lactic acidosis w/ excessive alcohol intake.