Metformin
Biguanide · Endocrine
Generic name: Metformin hydrochloride
Indications
- Type 2 diabetes mellitus
- PCOS (off-label)
- Pre-diabetes (prevention)
Dosing
- Adult
- 500 mg BD with meals, titrate to 2 g/day max (2.5 g TDS maximum)
- Paediatric
- 10+ years: 500 mg BD, max 2 g/day
Routes
- Oral
Contraindications
- eGFR < 30
- Severe hepatic impairment
- Contrast media (48h hold)
- Alcoholism
Side effects
- GI upset (nausea, diarrhoea)
- Lactic acidosis (rare)
- Vitamin B12 deficiency (long-term)
Monitoring
- eGFR before and annually
- Vitamin B12 every 1–2 years
Key interactions
- Alcohol (lactic acidosis risk)
- IV contrast (hold 48h before/after)
Reviewed by DocBuddy Clinical Team on . Written as a study aid for medical students. Always check a current local formulary before prescribing.
Practise the pharmacology
Questions on Metformin and the rest of endocrine pharmacology are in the app, with the drug cards a tap away while you answer.