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How and when to take metformin

Take metformin with or after a meal to reduce the side effects. Swallow them whole with water. Do not chew them.

Metformin tablets come in different strengths. Your GP will tell you how many tablets to take a day.

If you're taking the liquid version, use the plastic syringe or spoon that comes with your medicine to measure the dose. Do not use a kitchen teaspoon as you will not get the right amount.

When you first start taking metformin, your GP will increase the dose slowly. This reduces the chances of getting side effects.

If you take too much

Taking too much metformin can lead to serious health problems.

Emergency action required: Go to an emergency department (ED) immediately if:

  • you take too much metformin

Stop taking metformin. Bring the packet or leaflet and any remaining medicine with you.

Do not drive yourself to ED. Get someone else to drive you or call for an ambulance.

Symptoms of taking too much metformin

Taking too much metformin can cause symptoms quickly.

Symptoms can be severe and include:

  • stomach pain
  • difficulty breathing
  • feeling cold
  • unusual sleepiness
  • tiredness or weakness
  • vomiting
  • feeling unwell
  • reduced heartbeat

If you forget to take it

Do not take a double dose to make up for a forgotten dose.

If you miss a dose of metformin, take the next dose at the usual time.

Page last reviewed: 9 June 2024
Next review due: 9 June 2027