<human>:  What are the side effects of the medicine Metformin?
<bot>: The most common side effects of Metformin include nausea, diarrhea, flatulence, indigestion, headache, and a metallic taste in the mouth. Less common side effects include muscle pain, weakness, abdominal discomfort, and stomach pain. Other rare side effects include low blood sugar (hypoglycemia), vitamin B12 deficiency, lactic acidosis, and a loss of appetite.