Dr Amir Khan issues warning on 'super popular' everyday supplements

A health expert has issued a stark warning to anyone who routinely consumes supplements alongside doctor-prescribed medication, claiming the pairing may be more dangerous than you realise.

The supplement industry continues to thrive, with the market projected to grow from $164 billion (£121.9 billion) in 2025 to $284 billion (£211.1 billion by 2034, as per Vypr’s latest Emerging Trends report.

With 'super popular' supplements such as vitamin D, iron, probiotics, and creatine coming in a variety of forms, including pill, liquid, and powder form, and being stocked in supermarket shelves, it’s never been easier to start self-dosing.

But one TV doctor has warned against purchasing over-the-counter tablets on a whim, claiming it could have a serious knock-on effect, especially if you are currently using some prescribed medication.

Dr Amir Khan, who often features on ITV’s This Morning, issued the notice to his one million Instagram fans earlier this week.

He prefaced the caution: “Loads of people take them: magnesium, turmeric, St John’s wort, collagen, herbal remedies and I think many assume ‘well, it’s natural, so it should be safe’.

“But natural doesn’t automatically mean harmless,” Dr Khan stated. “Especially if you’re taking medication."

The expert said in his Instagram video that St John’s wort, which some people consume to combat their low moods, can easily interfere with antidepressants, the contraceptive pill, blood thinners, and other medications used after an organ transplant.

“It changes how your liver processes drugs,” he continued.

Dr Khan also said that people who use blood thinners, such as warfarin, should steer clear of turmeric, curcumin supplements, and vitamin K, as there is ‘concern about increased bleeding risk’.

Regularly consuming magnesium may also affect how well some medications, like antibiotics or thyroid medication, are absorbed, as can calcium, the medical professional warned.

“Even grapefruit juice - I know it isn’t technically a supplement but [it can impact] some medications because of the way it affects drug breakdown.”

To make sure you avoid any nasty health complications, Dr Khan has advised anyone thinking of consuming supplements to inform their GP first.

“Some [supplements] are genuinely helpful for the right person at the right dose for the right reason. But my message is simply this: if you’re taking regular medication, don’t forget to tell your doctor which supplements you also take.

“Because sometimes, the interaction we’re worried about isn’t between two medications, it can be between medicine and something you thought was harmless… Just let us know.”

Expert warning to anyone who takes vitamins every day

Dr Khan isn’t the only expert to express caution when it comes to supplements, with nutritionist Dr Carol Granger revealing last year that they can be as unhealthy for you as fast-food.

"People think supplements are healthy, and while some can be, others can be as detrimental to health as ultra-processed foods when taken regularly in large amounts,” she told the Express.

Meanwhile, Superdrug pharmacy superintendent Niamh McMillan warned that fat-soluble vitamins, such as vitamin D, should only be taken when necessary.

Taking too much of the vitamin every day can cause seizures and coma.

“There's certain vitamins that we don't pee out if we take too much, they're stored in the fat, so vitamins A, D, E, and K,” said Dr Zoe Williams, NHS GP and media medic.

When there is a supply in abundance, your body may create calcium deposits in your heart, your kidneys and your blood that can ‘make you feel unwell’, the expert said.

It’s also possible to overdose on vitamin A, causing pain and, in rare cases, death.

Speak to your healthcare provider if you’re unsure whether you really need to be taking vitamins. They can advise a dose for your specific needs.