org/wiki/Metformin
Contraindications
Metformin is contraindicated in people with any condition that could increase the risk of
lactic acidosis, including kidney disorders (creatinine levels over 150 μmol/l (1.7 mg/dL),[47] although this is an arbitrary limit), lung disease and liver disease. According to the prescribing information, heart failure, in particular, unstable or acute congestive heart failure, increases risk of lactic acidosis with metformin.