By Annette R. Karnash, R.N., M.N.
Metformin is generally not recommended for use in patients with congestive heart failure or renal dysfunction. Metformin has the potential to interfere with furosemide (a diuretic) and nifedipene (a calcium channel blocker), both prescribed for hypertension. There is a risk of lactic acidosis which can be fatal.
