Metformin does have several common side effects. Like almost all medications, metformin will affect different people in different ways.

The following lists detail Metformin’s side effects. However, this does not mean that all people taking the antidiabetic medication will experience any or all of the following side effects.

To make it easier to understand the prevalence of Metformin side effects, we have divided them by frequency.

Very common – affecting over 1 in 10 people taking Metformin

  • Disturbance to the gut
  • Nausea
  • Vomiting
  • Diarrhoea
  • Abdominal pain
  • Loss of appetite

Common – affecting between 1 in 10 and 1 in 100 people taking Metformin

  • Taste disturbance, usually a metallic taste

Very rare – affecting under 1 in 10,000 people taking Metformin

  • Elevated levels of lactic acid in the blood (lactic acidosis)
  • Decreased absorption of vitamin B12 during long-term use
  • Skin reactions such as rash, itching or flushing

To find out more about Metformin side effects, people with diabetes should discuss the medication with their doctor and read the information provided by the manufacturer.

The list of side effects above does not purport to be a full list of all recognised side effects of the drug.

What should I do if I experience Metformin side effects?

All medicines take some getting used to. You should speak to your doctor if any of the side effects become troublesome or painful.

If you find your breathing is being affected, along with drowsiness, dizziness and confusion you should stop taking Metformin at once and seek urgent medical attention.

These are the symptoms of lactic acidosis, a rare but very serious condition that can be caused by Metformin.

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