A pharmacist has warned people taking metformin, a common diabetes medicine, that certain over-the-counter painkillers could pose a risk. Raj Patel, known as the Straight-Talking Pharmacist on TikTok, highlighted that anti-inflammatory drugs such as ibuprofen and diclofenac can put extra strain on the kidneys, especially when dehydrated.
Kidney function and metformin
Metformin is used to treat type 2 diabetes, and the body removes the medicine through the kidneys. Mr Patel explained: "The main issue is your kidney function. It's because your kidneys remove metformin from your body." He added that painkillers bought without a prescription "can put extra strain on your kidneys, especially if you're dehydrated."
NHS guidance confirms that anti-inflammatory medicines, along with certain blood pressure drugs and diuretics, can interact with metformin or affect kidney function. This does not mean everyone taking metformin must avoid these medicines, but a pharmacist or doctor can check suitability and whether monitoring is needed.
Other interactions to consider
Mr Patel also noted that "some water tablets and blood pressure medicines can also affect kidney function. They're often prescribed safely with metformin, but you may need monitoring." Alcohol is another consideration, particularly heavy drinking or dehydration. "Too much alcohol can increase the risk of a rare serious condition called lactic acidosis, particularly if you're fasting, dehydrated or have a liver problem," he said.
Lactic acidosis is a rare but serious complication requiring urgent medical attention if suspected. The NHS advises people taking metformin to seek emergency help if they think they may be experiencing it.
Check before starting new medicines
Mr Patel urged people to check before starting anything new, including vitamins and supplements bought from a supermarket: "Before you start a new medicine, vitamin or supplement, even from the supermarket, ask your pharmacist, is this suitable with my metformin?" His final warning was not to make changes to prescribed treatment without advice: "Whatever you do, do not stop prescribed medicines by yourself."
