Generally speaking, taking metformin does not cause dry mouth. Metformin is a glucose-lowering drug that can be used to treat patients with type 2 diabetes who cannot control their blood sugar well with diet and physical exercise alone. Adverse effects include nausea, vomiting, loss of appetite, dizziness, rash, abdominal pain, diarrhea, and fatigue, but it does not usually cause dry mouth. Patients taking metformin are usually diabetic, and diabetes itself has the clinical manifestation of thirst, so the dry mouth symptoms in diabetic patients taking metformin may be caused by poor blood glucose control rather than by taking metformin. In addition, dry mouth symptoms can also be seen in dry syndrome, uremia and other diseases. It is recommended to go to the hospital if you experience dry mouth symptoms after taking metformin that are not relieved by drinking water.