NHS-sourced information. Always read the patient information leaflet (PIL) and speak to your pharmacist or GP before starting, stopping or changing this medication.
Metformin is a medicine used to treat Type 2 diabetes. It belongs to a group of medicines called biguanides. It is usually the first medicine prescribed when diet and exercise alone have not been enough to control blood sugar levels.
Metformin works by:
Unlike some diabetes medicines, metformin does not cause weight gain and is unlikely to cause hypoglycaemia (low blood sugar) when used alone.
Metformin is taken as tablets, usually 2-3 times a day with or after meals to reduce stomach upset. The dose is usually started low and gradually increased. A slow-release (modified-release) version taken once daily is also available.
Taking metformin with food or using the slow-release version can help reduce stomach side effects.
All medications can cause side effects, though not everyone gets them. The list below shows the most commonly reported effects. Contact your GP or pharmacist if you are concerned.
Always tell your doctor and pharmacist about all medicines you take, including vitamins, supplements, and over-the-counter products. Some interactions can increase side effects or reduce how well a medicine works.