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Promotes weight loss by regulating the body’s response to insulin, decreasing cravings, and lowering the tendency to store fat.

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Branded names

Fortamet®, Glucophage®, Glumetza®, and Riomet®

Conditions FDA-approved to treat

Type 2 Diabetes

Benefits for weight loss

Regulate insulin

Balance blood sugar

Reduce appetite

Decrease fat absorption

The results are in...

  • How it works

    Metformin is FDA-approved to improve blood sugar control in adults with type 2 diabetes mellitus when combined with diet and exercise. While not specifically approved for this use by the FDA, it is also commonly used by leading specialist obesity clinicians and weight clinics off-label to help promote weight loss by regulating the body’s response to insulin, decreasing cravings, reducing glucose production and lowering the tendency to store fat.

  • Form and dosing

    Metformin typically comes in a tablet form or as an oral solution with dosages starting at 500 mg. Dosing instructions vary according to weight, tolerability and other factors and should be discussed with your healthcare provider.

  • Common side effects
    • diarrhea
    • nausea/vomiting
    • upset stomach (gas, bloating, and stomach cramps)

What are doctors saying?

“Metformin is a plant-derived off-label option for weight loss, appetite control, and sugar/carbohydrate craving control. It may help people be more adherent to a low carbohydrate diet for those on that type of plan.”

— Dr. Rekha Kumar, Chief Medical Officer at Found

“Metformin is an effective drug to reduce weight in a naturalistic outpatient setting in insulin sensitive and insulin resistant overweight and obese patients.”

— PubMed

Medical Disclaimers

Metformin is only FDA-approved to treat type 2 diabetes. Prescribing medications are up to a medical provider’s discretion and may not be appropriate for everyone.

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Metformin warnings


Postmarketing cases of metformin-associated lactic acidosis have resulted in death, hypothermia, hypotension, and resistant bradyarrhythmias. Symptoms included malaise, myalgias, respiratory distress, somnolence, dizziness, changes in heart rate/rhythm, and abdominal pain. Laboratory abnormalities included elevated blood lactate levels, anion gap acidosis, increased lactate/pyruvate ratio; and metformin plasma levels generally >5 mcg/mL. In more than 20,000 patient-years exposure to metformin in clinical trials, there were no reports of lactic acidosis. Reported cases have occurred primarily in diabetic patients with significant renal insufficiency, including both intrinsic renal disease and renal hypoperfusion,often in the setting of multiple concomitant medical/surgical problems and multiple concomitant medications.Risk factors include renal impairment, concomitant use of certain drugs, age ≥65 years old, radiological studies with contrast, surgery and other procedures, hypoxic states, excessive alcohol intake, and hepatic impairment. Lactic acidosis is a medical emergency and requires immediate treatment in the hospital.


Before using metformin, tell your healthcare provider about your medical history, especially if you have:

  • kidney disease
  • heart disease or congestive heart failure
  • liver disease
  • metabolic acidosis or diabetic ketoacidosis
  • high ketone levels in your blood or urine
  • you use insulin or other diabetes medications

Talk to your healthcare provider if you are planning to become pregnant or if pregnant or breastfeeding. Avoid alcohol while taking this medication. Talk to your healthcare provider about discontinuing metformin prior to a surgical procedure or an iodinated contrast imaging procedure. Stop metformin and notify your healthcare provider immediately if you have an illness with severe diarrhea and/or vomiting resulting in dehydration.

Side effects information

Many people experience no side effects while taking metformin. The most common side effects of metformin include:

  • diarrhea
  • nausea/vomiting
  • upset stomach (gas, bloating, and stomach cramps)

These symptoms may subside after the body adjusts to the medication. Taking your medicine with the evening meal can help reduce these side effects.

Additional but rare side effects include:

  • low blood sugar (hypoglycemia)
  • feeling cold
  • unusual muscle pain
  • dizziness
  • slow or irregular heart rate
  • trouble breathing
  • metallic taste
  • changes to nails on fingers and toes
  • low b12 levels

Drug interactions

As with other medications, metformin can interact with alcohol and certain medications, including angiotensin-converting enzyme (ACE) inhibitors, beta-blockers, corticosteroids, morphine, hormone replacement therapy and estrogens, oral contraceptives, carbonic anhydrase inhibitors, nifedipine, thiazides or furosemide and other diuretics, phenothiazines, phenytoin, nicotinic acid (niacin), multidrug and toxin extrusion inhibitors, sympathomimetics, calcium channel blockers, isoniazid (antibiotic for tuberculosis), insulin and glyburide or other medications for diabetes, and medications for thyroid disease.

Please consult the pharmaceutical packaging for a full list of side effects, warnings, interactions and additional information.

To report suspected adverse reactions to metformin contact the FDA at 1-800-FDA-1088 or

In case of emergencies, please call 911 or go to the nearest emergency room.