Whether you’re a marathon runner or struggling with arthritis, why you should be careful about taking anti-inflammatories, says PROFESSOR ROB GALLOWAY

This coming Sunday over 50,000 people will be taking part in the London ­Marathon; that’s just over 26 miles of blood, sweat and tears — and then adrenaline, as the runners cross the finish line.

They will end the day with lifelong memories, raise millions for charity and, crucially, get a massive health boost from the months of training.

However, although the benefits of ­running far outweigh the harms if you’re otherwise healthy, there are risks: and some won’t finish the race and may end up with a serious medical emergency.

Many of you reading this will never go on a long run and may well be thinking none of this is relevant to you.

But if you take anti-inflammatory ­tablets such as ibuprofen or use a ­painkilling anti-inflammatory gel, think again.

Let me explain: two weeks ago it was the Brighton Marathon, where I have been the medical director for the past 12 years. I have seen the problems a massive run can cause, and this year was no exception.

As I write, one of our runners is still in hospital because of heatstroke and ­kidney failure, his life saved by the ­medical team on the course.

In his 20s, he was just coming towards the end of the race when he collapsed. His temperature was over 41c (106f) and we used a specially designed cooling pod (I-CWIK) developed by the ­military. This young man is now on dialysis because running this race damaged his kidneys so badly.

Heatstroke and kidney failure may well have claimed the life of the legendary Greek soldier Pheidippides in 490BC — after running from Marathon to Greece to proclaim ‘Victory’ he dropped down dead (his feat was ­commemorated in the first ­marathon held in the 1896 Greek Olympics).

While we don’t fully understand the complexities of these two conditions, something the Brighton marathon runner told me has implications not just for next Sunday’s runners, but for all of us. (And helps explain why this otherwise fit and healthy man became so dangerously ill).

The day after his run, he said that to avoid developing knee pain during the marathon, he took an ibuprofen tablet just in case as he was setting off.

Anti-inflammatory tablets such as ibuprofen, naproxen and even gels such as Voltarol are types of NSAIDs — non-steroidal anti-inflammatory drugs. They work by inhibiting an enzyme called cyclooxygenase (COX), which is involved in inflammation.

During strenuous physical ­activity and in hot weather, the body loses its ability to regulate temperature (partly because of increased heat production from the muscles working so hard; while dehydration and blood flow being directed away from the skin to the vital organs mean you sweat less).

NSAIDs make this worse, in a number of ways, including reducing the kidneys’ ability to control fluid balance in the blood. But not everyone is affected in the same way.

In a study published late last year in the Journal of Science and Medicine in Sport, we gave runners tiny thermometers they swallowed before the race: the results showed that some runners who experienced temperatures of over 40c (104f) had no symptoms, whereas others ­suffered heatstroke (with symptoms such as confusion, muscle rigidity and kidney failure).

So something else apart from body temperature was at play causing them to collapse. One theory is that heat — from hot weather or strenuous exercise — causes bacteria to seep out from the intestines. NSAIDs — even a one-off tablet as per our Brighton runner — can also make our gut more leaky. The bacteria enters the bloodstream and can cause symptoms akin to sepsis — low blood pressure, confusion and high heart rate.

In addition, after running, some people have a higher amount of muscle damage which produces a protein in the blood — creatine kinase — which stops the kidneys working. And yes, NSAIDs also reduce the blood flow to the ­kidneys. So a perfect storm for kidney failure.

There is an important message for this in non-runners, too.

A couple of years ago, a 58-year-old carpet fitter came to A&E lethargic, with poor concentration and itching. Blood tests showed he was in urgent need of kidney dialysis.

And after assessing him, the cause became clear: he had developed knee pain after years and years of kneeling. Self-employed, he couldn’t afford a day off work and so would pop ibuprofen daily, as well as liberally using Voltarol gel. His long-term use of NSAIDs had caused kidney failure.

While the dialysis machine took over the function of his failing kidneys, stopping the anti-­inflammatory medications allowed his kidneys to heal and so two weeks later he was out of hospital and off dialysis. But it had been a close shave.

When it comes to marathon running, is it just the tablets that are dangerous or are the gels also a risk? The answer is we are not sure: we know gel gets absorbed into the blood and so could ­theoretically cause problems, especially when excessively used.

This is why for the Brighton Marathon (now organised by London Marathon Events) runners were sent specific pre-race medical advice stating: ‘Do not take any anti-inflammatory ­medications before, during or for 24 hours after the marathon . . . ­Anti-inflammatory gels are safer than tablets but can also cause problems during marathon ­running and so avoid them before or during the event.’

Sadly, most people do not read the advice sent out and get advice from friends or social media.

It’s not just a one-off for endurance exercise that’s a worry: using them over a prolonged period, whoever you are, is a risk.

This includes the gels as well as the tablets. Indeed, Voltarol gel states on its product information leaflet that it must not be used for longer than 14 days.

While most people will know about the risks of NSAIDs taken long-term in terms of gut problems, such as bleeding, many will be oblivious to the risks of kidney problems and heatstroke.

So when it comes to the ­summer, it’s so important to avoid long-term use of these drugs — and try to avoid heatstroke, especially if you’re older because poorer ­kidney function with age puts you at a higher risk.

This, combined with warning that NSAIDs are linked to a greater risk of heart attack, heart failure and stroke (inhibiting inflammation also leads to water and salt retention, and higher blood pressure), is why I now advise my patients to take them only for a short period.

When I myself am about to do a long run, I avoid any form of NSAID, even as a one-off dose.

And for those in chronic pain, such as from arthritis, my advice is to seek other forms of relief — such as heat-type gels, cold-water swimming and paracetamol.

We have become over­medicalised when it comes to managing pain and we don’t always think about the side-effects of medications.

NSAIDs may provide temporary relief, but long-term they can be very risky.

As for runners, a one-off dose of a NSAID before a race may help you get to the start line, but they could risk you getting to the ­finish line safely.

As my patient told me as I left his intensive care bedside: ‘I had no idea that my ibuprofen tablet could cause my problems. Please tell others so they know and don’t suffer like I have.’

@drrobgalloway