Pharmacist tells millions using metformin for diabetes you're not imagining strange side effect

 A pharmacist has reassured patients taking metformin they might not be imagining an unusual issue. Figures show there are around six million people in the UK with diabetes with many taking metformin to tackle the condition.

Latest figures show pharmacists in England dispensed more than 26 million prescriptions for the drug in 2024 with it being the first-line treatment for up to nine out of 10 patients. However, while being a very successful medication, it does come with some side effects, with many of them experienced by those using the medication.

The most common of these include feeling sick or having diarrhoea when first starting taking metformin, stomach ache or having a lack of appetite. However there is another common side effect which affects the way things taste.

Raj R Patel, posting on TikTok as Pharmacist Health Raj, asked his followers: "Does your mouth suddenly taste like you’ve been sucking a coin? If you take metformin, your medicine could be part of the reason.

"A change in taste is a recognised common side effect of metformin in UK prescribing information — meaning it can affect between 1 in 100 and 1 in 10 people taking it. And Diabetes UK specifically describes a metallic taste in the mouth as something people can experience while taking metformin.

"So if coffee suddenly tastes strange, food tastes different or you keep getting that unmistakable metallic, coin-like taste don’t immediately assume you’re imagining it. Your medicine is one possible explanation."

But the expert warned there is "an important bit of balance" as metformin is not the only reason somebody can develop a metallic taste. He said other possible causes include:

• gum or dental problems

• colds or sinus problems

• indigestion

• pregnancy

• changes to your sense of smell

• other medicines

The pharmacist adds: "So look at the timing. Did the taste change start after beginning metformin or changing your treatment?

"That is useful information to take to your pharmacist or prescriber. The current NHS metformin guidance lists a change in the way things taste among common side effects and says that many metformin side effects ease after the first couple of weeks as the body adjusts — although some can last longer."

He said Diabetes UK had advice for people with the problem, suggesting that some people find sugar-free chewing gum helpful for the metallic taste.

Raj adds: "Please don’t stop prescribed metformin just because your taste has changed. The NHS advises keeping the medicine unless you’ve been told to stop, and speaking to a pharmacist or doctor if a side effect is bothering you or does not go away."

According to Diabetes UK almost six million people in the UK have diabetes. However while of these more than 4.7 million have been diagnosed with the condition almost 1.3 million do not know they have it.

Figures show an estimated 3.9 million people in England take glucose-lowering medication for diabetes with metformin being the most common first-line treatment.