Anorexia, dyspepsia, flatulence, metallic taste, nausea, vomiting, headache and weight loss are the most common side effects.
Lactic acidosis, a serious, potentially fatal side effect may occur rarely. Patients should be informed of the risks of lactic acidosis and its symptoms (diarrhea, fast and shallow breathing, unusual tiredness and weakness, sleepiness, muscle pain or cramping). If lactic acidosis does occur, immediate emergency hospitalization is required.