Metformin is a medicine used to treat type 2 diabetes and sometimes polycystic ovary syndrome (PCOS).
Type 2 diabetes is an illness where the body doesn't make enough insulin, or the insulin that it makes doesn't work properly. This can cause high blood sugar levels (hyperglycemia).
PCOS is a condition that affects how the ovaries work.
Metformin lowers your blood sugar levels by improving the way your body handles insulin. It's usually prescribed for diabetes when diet and exercise alone have not been enough to control your blood sugar levels.
For women with PCOS, metformin stimulates ovulation even if they don't have diabetes. It does this by lowering insulin and blood sugar levels.
Metformin is available on prescription as tablets and as a liquid that you drink.
Metformin works by reducing the amount of sugar your liver releases into your blood. It also makes your body respond better to insulin. Insulin is the hormone that controls the level of sugar in your blood.
It's best to take metformin with a meal to reduce the side effects.
The most common side effects are feeling sick, vomiting, diarrhoea, stomach ache and going off your food.
Metformin does not cause weight gain (unlike some other diabetes medicines).
Metformin may also be called by the brand names Bolamyn, Diagemet, Glucient, Glucophage, and Metabet.
Like all medicines, metformin can cause side effects, although not everyone gets them.
Common side effects
Common side effects happen in more than 1 in 100 people. Talk to your doctor or pharmacist if these side effects bother you or don't go away after 1 week:
feeling sick
vomiting
diarrhoea
stomach ache
loss of appetite
a metallic taste in the mouth
Serious side effects
Serious side effects are rare and happen in less than 1 in 10,000 people.
Tell your doctor straight away if you get warning signs of:
a general feeling of discomfort with severe tiredness, fast or shallow breathing, being cold and a slow heartbeat
yellowing of the skin or whites of the eyes - this could be a sign of liver problems
extreme tiredness, lack of energy, pins and needles, a sore and red tongue, mouth ulcers, muscle weakness and disturbed vision - these could be signs of anaemia
a skin rash, redness or itching - this could be a sign of a skin disorder
Serious allergic reaction
In rare cases, it’s possible to have a serious allergic reaction to metformin.