Not recommended w/ alcohol. Intravascular administration of iodinated contrast agents may lead to contrast-induced nephropathy, resulting in metformin accumulation & increased risk of lactic acidosis. May increase risk of lactic acidosis w/ NSAIDs, COX-II inhibitors, ACE inhibitors, AIIAs & loop diuretics; ranolazine, vandetanib, dolutegravir, & cimetidine. Intrinsic hyperglycemic activity w/ systemic & local glucocorticosteroids, β
2-agonists & diuretics. May decrease blood glucose levels w/ ACE inhibitors. Small effect on plasma digoxin conc.