metformin
Brand names: Glucophage, Glumetza, Fortamet, Kazano, Jentadueto, Kombiglyze, Janumet, Invokamet, Xigduo, Synjardy, Segluromet, Trijardy, Zituvimet, Riomet, Actoplus Met
Medically Reviewed by Dr. Sarah Chen, PharmD, BCPS
Clinical Pharmacist & Medical Reviewer
Last reviewed: March 19, 2026
Metformin (brand name: Glucophage) is the first-line oral medication for type 2 diabetes. It works by reducing glucose production in the liver and improving insulin sensitivity in muscle and fat tissue..
Typical Cost
$4–$15/month
Forms
tablet +2
Status
Rx
Generic
Available
Metformin hydrochloride is the lowest-cost Biguanides at $4-$25/month/month
Uses & Indications
Metformin is indicated as an adjunct to diet and exercise to improve glycemic control in adults and pediatric patients 10 years and older with type 2 diabetes mellitus. It is also used off-label for polycystic ovary syndrome (PCOS) and weight management.
Dosage & Administration
Initial dose: 500 mg twice daily or 850 mg once daily with meals. Titrate gradually to reduce GI side effects. Maximum dose: 2550 mg/day in divided doses. Extended-release formulations may be taken once daily with evening meal.
How It Works
Metformin activates AMP-activated protein kinase (AMPK) in the liver, reducing hepatic gluconeogenesis. It also increases peripheral glucose uptake and utilization, and decreases intestinal glucose absorption.
Side Effects
Serious Side Effects
Common Side Effects
Rare Side Effects
Warnings & Precautions
Risk of lactic acidosis (rare but serious). Temporarily discontinue before surgery or procedures requiring contrast dye. Monitor renal function. May cause vitamin B12 deficiency with long-term use.
Contraindications
Contraindicated in patients with eGFR < 30 mL/min/1.73m², active or unstable heart failure, metabolic acidosis, or history of lactic acidosis. Withhold before procedures using iodinated contrast media.
Frequently Asked Questions
What is metformin used for?
Metformin is primarily used to treat type 2 diabetes. It is also used off-label for polycystic ovary syndrome (PCOS) and to help prevent diabetes in people at high risk.
When should I take metformin?
Metformin should be taken with meals to reduce stomach upset. If taking twice daily, take one dose with breakfast and one with dinner.
What are the most common side effects of metformin?
The most common side effects are gastrointestinal: nausea, diarrhea, vomiting, and stomach discomfort. These usually improve after the first few weeks and can be minimized by starting at a low dose and taking with food.
Can metformin cause low blood sugar?
Metformin alone rarely causes hypoglycemia (low blood sugar) because it does not stimulate insulin secretion. However, the risk increases when combined with insulin or sulfonylureas.
Medical Disclaimer
The information on RxGuide is intended for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician, pharmacist, or other qualified health provider with any questions you may have regarding a medical condition or medication. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.