The main side effects of Metformin extended-release tablets include digestive symptoms, headache, fatigue, and lactic acidosis. The most common side effects of metformin extended-release tablets are digestive symptoms, including abdominal pain, diarrhea, loss of appetite, nausea, and vomiting. Gastrointestinal adverse effects can be minimized by taking the medication with meals, starting with a small dose and gradually increasing the dose. Metformin extended-release tablets may also cause adverse reactions such as headache, fatigue, and rash. Metformin is able to lower blood glucose by inhibiting hepatic gluconeogenesis, which means that it reduces the chances of lactic acid isomerization to glucose in the body, a condition that may cause lactic acid to build up in the body, resulting in lactic acidosis. However, this side effect is less likely to occur. Note that this medication is contraindicated in severe infections, hypoxia, trauma, major surgery, pregnant and lactating women. Metformin is a common clinical hypoglycemic drug and should be used appropriately under the supervision of a physician.