Can supplements interact with your medication? Check first

I asked Dennis Gore, 60 years a pharmacist, for his top five supplements for anyone over 40.

His first answer wasn't a supplement. It was a rule: if you're already on medication from the doctor, check with your doctor or pharmacist first.

Only then did he talk about the ones he likes, including selenium, magnesium, collagen with glucosamine and chondroitin, and vitamin D. And later, straight after praising a supplement made from French pine bark, he added the caution again: if you're on blood thinners or other medicines, be careful, and be sensible.

That order is the whole lesson. Can supplements interact with your medication? Some can, which is exactly why the check comes first.

Natural doesn't mean it can't interact

Supplements and herbal remedies are easy to buy and easy to think of as harmless. But anything that does something in your body can also change how a medicine works.

The NHS is clear about herbal medicines: some medicines don't mix well with them, and taking both can cause harmful effects or stop your medicine working. Among the examples it lists are statins, some antidepressants, metformin, ramipril, warfarin and the combined contraceptive pill. Its advice is to check with a pharmacist first if you already take other medicines, including ones bought without a prescription.

For warfarin, the NHS goes further: there isn't enough information to say other herbal remedies and supplements are safe to take with it, so tell your doctor or pharmacist about any vitamins or supplements you take.

Remove harm before adding benefit

This is where the founding principle earns its place. Before you add anything new, know what's already in the mix. The most useful supplement advice you'll get this year might be what you don't add, or what you stop doubling up on.

The ten-minute cupboard check

1. Gather everything in one place: prescribed medicines, anything bought at the pharmacy or supermarket, vitamins, minerals, herbal remedies, protein powders, 'immune' drinks and sleep aids.
2. Write it all down with the strength and how often you take it. A photo of each label works too.
3. Take the list to your pharmacist, or bring it to your next medication review with your GP.
4. Make no changes to a prescribed medicine on your own. If something on the list raises a question, that's a conversation with your GP or pharmacist, not a decision for the kitchen table.

Questions worth asking

• Does anything here interact with my medicines?
• Am I doubling up? The same ingredient often turns up in a multivitamin and a separate supplement.
• Does anything need taking at a different time of day from my medicines?
• Is there anything here I'm taking without a clear reason?
• If I'm going to add something, which one is worth trying first, and how will I know if it's helping?

Why this matters more after 40

Our forties and fifties are often when two things happen at once. The first regular prescription arrives, perhaps for blood pressure or cholesterol. And we start reading about supplements for joints, energy or sleep. Each decision makes sense on its own. Put together, without anyone looking at the whole list, they can overlap in ways nobody planned.

It's rarely dramatic. More often it's quiet: a medicine that doesn't work as well as it should, or two products that both contain the same ingredient.

A common example: doubling up

Vitamin D is a good one to check. It turns up in a multivitamin, in a separate vitamin D supplement, sometimes in a calcium combination, and in some fortified foods and drinks. Each label looks reasonable. Added together, the total can be more than you meant to take. The same goes for zinc, iron and vitamin A, which appear in all sorts of combination products.

That's not a reason to worry. It's a reason to look at the labels side by side, once, with someone who knows what they're reading.

Quick answers

Which supplements interact with medication? It depends on the medicine and the supplement, which is why a pharmacist check is worth more than a general list. The NHS names medicines including statins, warfarin, metformin and the combined pill among those that don't mix well with some herbal medicines.

Can I ask a pharmacist without a prescription? Yes. Take your list to your local pharmacy and ask; you don't need a prescription to ask for advice.

Should I stop a medicine if I'm worried? No. Keep taking it and speak to your GP or pharmacist first.

Then, and only then, add

A shorter list you understand beats a long one you don't. Once you know what's already in the mix, add one thing at a time and give it long enough to judge.

Everyone is different

What suits one person can be wrong for another, especially with medicines in the picture. Age, other health conditions, pregnancy, surgery coming up and the medicines you take all change the answer. That's why the check comes first.

Dennis Gore is a natural health legend: at his Prestwich pharmacy since 1966, and formerly on BBC Radio Manchester, Granada TV and online shows. Dennis's consultations are his own, separate from Just Ask Omar.

Sources: NHS: Herbal medicines (accessed 1 November 2026); NHS: Taking warfarin with other medicines and herbal supplements (accessed 1 November 2026).