People taking a common medication have been urged to seek immediate help if they spot a symptom in their eye. This side effect of metformin could be an indicator of serious liver problems.

Metformin is one of the most widely prescribed drugs in the world, with around 200 million people globally thought to be taking it. It is mainly used to treat type 2 diabetes and gestational diabetes.

It's also used to help prevent type 2 diabetes if you're at high risk of developing it. Further to this, metformin can be used to improve fertility if you have polycystic ovary syndrome (PCOS).

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However, as with any medication, it can cause side effects. Often, these are not serious and can be treated, such as nausea, loss of appetite, and stomach ache.

However, if these side effects don’t go away and are bothering you, you should speak to a doctor or pharmacist. But other side effects can be more serious and need immediate medical attention.

On the NHS website, the health body explained that serious side effects of metformin as “rare” and happen in “less than one in 10,000 people”. If you experience any of these, the NHS said you should “call your doctor or call 111 straight away”.

This includes jaundice, which you might notice in your eyes or skin. The NHS said: “The whites of your eyes turn yellow, or your skin turns yellow, although this may be less obvious on brown or black skin – this can be a sign of liver problems.”

The health body also urged people to seek help if “you get a general feeling of being unwell with severe tiredness, fast or shallow breathing, being cold and a slow heartbeat”.

The NHS lists common side effects of metformin as:

• Feeling sick (nausea)


• Being sick (vomiting)


• Diarrhoea


• Stomach ache


• Loss of appetite


• A metallic taste in the mouth

It also warned the drug can cause a vitamin B12 deficiency and low blood sugar for which you may need to speak to your doctor.

In rare cases, it's possible to have a serious allergic reaction (anaphylaxis) to metformin. The NHS said you should call 999 now if:

• Your lips, mouth, throat or tongue suddenly become swollen


• You're breathing very fast or struggling to breathe (you may become very wheezy or feel like you're choking or gasping for air)


• Your throat feels tight or you're struggling to swallow


• Your skin, tongue or lips turn blue, grey or pale (if you have black or brown skin, this may be easier to see on the palms of your hands or soles of your feet)


• You suddenly become very confused, drowsy or dizzy


• Someone faints and cannot be woken up


• A child is limp, floppy or not responding like they normally do (their head may fall to the side, backwards or forwards, or they may find it difficult to lift their head or focus on your face)

The NHS added: “You or the person who's unwell may also have a rash that's swollen, raised, itchy, blistered or peeling. These can be signs of a serious allergic reaction and may need immediate treatment in hospital.”

For more information, visit the NHS website here.