Metformin should be stopped temporarily if a patient is having any type x-ray that requires dye injected into the vein. Patient should stop taking if nausea, vomiting or dehydration is experienced.

Extended relief metformin should be swallowed whole. A shell may be seen in the stool and is not a problem.

Symptoms requiring a patient to seek emergency medical attention include weakness, increased sleepiness, slow heart rate, light-headedness, fainting, cold feeling, stomach pain, shortness of breath, and muscle pain. These symptoms are indicative of a condition called lactic acidosis.