Metformin
Also sold as: Glucophage, Neodipar, Glycomet
Usual adult dose
Usual adult dose: start with 500 mg once or twice a day with meals; your doctor increases it slowly. Usual maximum is 2 g a day (up to 3 g in some patients). Take with food to reduce stomach upset.
Your doctor may give you a different dose. Children's doses depend on weight.
Side effects
Common
- nausea
- diarrhoea
- stomach pain
- metallic taste
- loss of appetite
Serious — get help
Stop taking it and see a doctor straight away if you notice:
- lactic acidosis (fast breathing
- severe muscle pain
- extreme weakness)
- low vitamin B12 with long use
Do not take it, or take care, if
- Severe kidney disease
- Severe liver disease or heavy alcohol use
- Severe infection, dehydration or shock
- Stop temporarily before surgery or X-ray tests with contrast dye (ask your doctor)
- Type 1 diabetes (not used alone)
Interactions
Medicines that can react with this one.
Moderate2 medicinesTake together only with care. Ask your doctor or pharmacist.
- Prednisolone
Steroids raise blood sugar and can reduce the effect of metformin; sugar should be checked more often.
- Tenofovir + Lamivudine + Dolutegravir
Dolutegravir raises metformin levels; the metformin dose may need lowering.
Minor2 medicinesUsually not a problem, but tell your doctor.
- Cyanocobalamin
Long-term metformin can lower vitamin B12 levels; B12 may need checking.
- Furosemide
Furosemide can change metformin levels and may affect kidney function; monitor blood sugar and kidneys.