Your safety is our first priority. Learn more about key medication details, possible side effects, warnings, and other important information about metformin below.
Prescribing Information
Metformin is a biguanide prescription medication approved to improve blood-sugar control in patients with type 2 diabetes when used with diet and exercise. It may also be prescribed off-label for other provider-determined metabolic concerns.
Black Box Warning
Metformin carries a boxed warning for metformin-associated lactic acidosis, a rare but potentially fatal buildup of lactic acid. Risk is higher with significant kidney impairment, severe infection or low-oxygen states, liver impairment, excessive alcohol use, certain medications, surgery, and iodinated contrast procedures.
Common Side Effects
Common or possible side effects may include:
- Diarrhea
- Nausea or vomiting
- Gas
- Abdominal discomfort
- Indigestion
- Reduced appetite
- Weakness
- Headache
- Metallic taste
Important Safety Information
Do not use metformin if you have severe kidney impairment, acute or chronic metabolic acidosis including diabetic ketoacidosis, or a known allergy to metformin.
Tell your provider about kidney or liver disease, heart failure, heavy alcohol use, severe infection, dehydration, planned surgery, or planned imaging with iodinated contrast. Metformin may need to be held around certain procedures or acute illnesses.
Long-term metformin use may lower vitamin B12 levels. Periodic blood counts, kidney testing, and vitamin B12 monitoring may be appropriate. Low blood sugar is more likely when metformin is combined with insulin or medications that increase insulin release.
Seek emergency medical help for unusual weakness, severe sleepiness, muscle pain, trouble breathing, persistent abdominal pain, feeling cold, dizziness, or a slow or irregular heartbeat, which may be symptoms of lactic acidosis.
To report suspected adverse reactions, contact the FDA at 1-800-FDA-1088 or visit www.fda.gov/medwatch.
