Metformin: Uses, Side Effects, and How to Take It Safely
Metformin is a prescription medicine used to help control blood sugar in adults and children with type 2 diabetes. It is sometimes used with other diabetes medicines or on its own. It does not replace insulin for people with type 1 diabetes.
Metformin usually lowers blood sugar and is taken with meals. Start, change, or stop doses only as directed by your doctor or pharmacist, because the right amount depends on your health, kidney function, and other medicines.
Key facts at a glance
- ATC
- A10BA02
- Generic
- Metformin
- Class
- biguanide
- Brands
- —
- Availability
- rx
- Pregnancy
- B
- Half-life (h)
- 6.2
- Routes
- oral
- Forms
- —
- Regions
- —
- Monitoring
- —
This page is for informational purposes only.
Do not use this information to diagnose yourself or to replace a physician's advice. Always consult a qualified healthcare provider before starting, stopping, or changing any medication. If you believe you are experiencing a medical emergency, call your local emergency number immediately.
Dosage and administration
- Usual dose
- 500mg twice daily
- Maximum
- consult physician
- Frequency
- every 12 hours
- Instructions
- Follow physician instructions
- Duration limits
- as prescribed
- Monitoring
- standard
- Usual dose
- 250mg twice daily
- Maximum
- consult physician
- Frequency
- every 12 hours
- Instructions
- Follow physician instructions
- Duration limits
- as prescribed
- Monitoring
- standard
- Usual dose
- 400mg daily
- Maximum
- consult physician
- Frequency
- once daily
- Instructions
- Follow physician instructions
- Duration limits
- as prescribed
- Monitoring
- standard
Overdose information
Special Populations
11 groupspregnancy
first trimesterreview necessity and consider discontinuation
use only if clearly needed and benefits outweigh potential risks
regular prenatal monitoring and blood glucose control
Use with caution and monitor for adverse effects.
pregnancy
second trimestermay require adjustment based on glycemic control
continue only if benefits outweigh risks
regular fetal growth monitoring
Use with caution and monitor for adverse effects.
pregnancy
third trimesterconsider discontinuation near term
may be continued until delivery if needed for glycemic control
fetal monitoring and glycemic monitoring
Use with caution and monitor for adverse effects.
lactation
breastfeedingno adjustment needed
considered compatible with breastfeeding
monitor infant for hypoglycemia
geriatric
elderlystart at low dose and titrate slowly
assess renal function before initiating and periodically during treatment
regular renal function monitoring every 3-6 months
Use with caution and monitor for adverse effects.
pediatric_age
adolescents 10 17 yearsstart with lower dose and titrate
approved for type 2 diabetes in pediatric patients 10 years and older
regular glycemic monitoring and growth assessment
renal_impairment
mild renal impairmentdose reduction may be required
monitor renal function regularly and adjust dose accordingly
monitor renal function every 3-6 months
Use with caution and monitor for adverse effects.
renal_impairment
moderate renal impairmentsignificant dose reduction required
use with caution and close monitoring
frequent renal function monitoring
Use with caution and monitor for adverse effects.
renal_impairment
severe renal impairmentavoid use
contraindicated in patients with serum creatinine above acceptable limits
regular monitoring if used off-label
Use of this medication in this population requires careful consideration of risks and benefits.
hepatic_impairment
moderate hepatic impairmentconsider dose reduction
use with caution due to reduced gluconeogenesis
monitor liver function and lactic acid levels
Use with caution and monitor for adverse effects.
hepatic_impairment
severe hepatic impairmentavoid use
contraindicated in significant hepatic disease
monitor liver function tests
Use of this medication in this population requires careful consideration of risks and benefits.
Statistics and clinical data
Commonly prescribed since
Metformin FDA approval year for type 2 diabetes
Drug class
Antidiabetic agent classification
Common uses
First-line treatment for type 2 diabetes
Primary mechanism
How Metformin works to lower blood glucose
Contraindications
Conditions and patient states where this medication should be avoided or used with caution.
Do not use (1)
Known allergy to this medication or its components
Use caution (1)
Consult healthcare provider for benefits vs risks assessment
Official drug label
WellAlly may earn a referral fee from linked resources at no extra cost to you. Editorial content is never influenced by commercial relationships.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 24, 2026. · Read our editorial policy