Metformin

Also sold as: Glucophage, Neodipar, Glycomet

Prescription neededDiabetes tablets

Comes as:Tablet

Usual adult dose

Diabetes tablets

Metformin

Also sold as: Glucophage, Neodipar, Glycomet

Prescription neededDiabetes tablets

Comes as:Tablet

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.