Common adverse effects of metformin include nausea, vomiting, diarrhea, weakness, and headache, while other adverse effects include hypoglycemia, myalgia, dizziness, and excessive sweating. Metformin is a common type of biguanide hypoglycemic drug. Some patients may experience common gastrointestinal adverse reactions such as nausea, vomiting, diarrhea, abdominal pain, and loss of appetite after applying metformin, and some patients may also experience adverse reactions such as hypoglycemia, myalgia, dizziness, lightheadedness, abnormal bowel movements, excessive sweating, chills, palpitations, weight loss, and hot flashes. Metformin is used clinically for the treatment of type 2 diabetes mellitus that is poorly controlled by physical activity and food. People with drug allergy, severe renal failure, severe infection, trauma, liver insufficiency, and acute alcoholism should not be treated with metformin. To summarize, patients must take metformin under the guidance of a doctor, do not self-medicate, so as not to affect the therapeutic effect.