This is a less common but serious side effect of the widely-prescribed drug taken by millions of Brits see more...

People taking a widely-prescribed medication are being urged to "call 111" if they notice a particular side effect affecting their eyes. While uncommon, this is a potentially "serious" symptom that necessitates medical attention.

Amitriptyline is a prescription antidepressant used to treat depression and low mood. It functions by increasing levels of serotonin, a chemical in the brain. The medication is also prescribed for nerve pain and migraine prevention. It ranks amongst the most frequently prescribed drugs in the UK, with between 15 and 16 million prescriptions dispensed annually.

However, as with all medications, amitriptyline can produce side effects in certain people. That said, the NHS notes that many people experience "no side effects" or "only minor ones".

On its website, the health service identifies eye pain as an uncommon but serious side effect of the medication. It advises that you should contact a doctor or 111 if "you have eye pain, a change in your eyesight, or swelling or redness in or around your eye".

Another serious side effect of amitriptyline is jaundice, which signals a potential liver problem. This can also manifest in the eyes.

The NHS states: "If the whites of your eyes turn yellow, or your skin turns yellow, although this may be less obvious on brown or black skin, or you have dark pee – these can be signs of a liver problem."