NSAIDs in sport

Non-steroidal anti-inflammatory drugs, or NSAIDs, can reduce pain sensations. In a previous blog, we discussed the mechanisms of NSAIDs action. This blog discusses the use, as well as contraindications to the use of NSAIDs in an athletic arena. When used in a sport setting, such as during endurance running, NSAIDs can compromise gut integrity, kidney function and cardiovascular health. Despite these risks, many athletes still use them. Below we outline the risks and describe why it is best to avoid NSAIDs during sport.

The use of NSAIDs among athletes

I’ve run a bunch of marathons and ultras in my time. It’s rare to see NSAIDs at an aid station alongside the jellybeans and sausage rolls, and yet it happens. That’s right, as runners were grabbing handfuls of crisps and tipping water on their heads, they also had the option of popping a few pills from an open packet of ibuprofen. I’ve seen it twice, to be exact, in races I contested some years ago. And it’s twice too many.

You wouldn’t get away with it today. Major running organisations like Ultra Trail du Mont Blanc (UTMB) have banned NSAIDs in competition, while others, such as the London Marathon and Western States Endurance Run (WSER), strongly discourage their use during events and for 48 hours before and after. Sports medics rarely prescribe NSAIDs anymore, even for injuries (1). And for good reason, which we’ll get to shortly.

And yet, our collective NSAID habit isn’t going anywhere. One study found ibuprofen in the urine of 22% of runners at UTMB (before the ban was imposed) (2), and another reported that 67% of runners use NSAIDs before, during, or after races from 10K to marathon (3). Despite the warnings, many athletes still pack NSAIDs with their gels, bibs, and blister tape. So, what are NSAIDs? And why are you being told to avoid them in races?

The mechanisms of NSAIDs action

As we discussed in a previous blog, NSAIDs are synthetic drugs that block prostaglandins, which are involved in inflammation and the sensitisation of pain receptors. More specifically, NSAIDs inhibit cyclooxygenase (COX) enzymes (COX-1 and COX-2) which are responsible for prostaglandin production. In short, NSAIDs inhibit the production of COX, block prostaglandins, and attenuate inflammation and pain. They’re not banned by WADA (the World Anti-Doping Agency) because they’re not performance-enhancing, per se, but rather performance-enabling, allowing you to perform through the pain. When your body sounds the alarm bells due to muscle damage or injury, NSAIDs effectively reduce the volume. That may sound like an advantage, but it's a dangerous illusion.

NSAIDs are not performance-enhancing, per se, but rather performance-enabling, allowing you to perform through the pain.

The double-edged sword of NSAIDs use

Inhibiting COX enzymes doesn’t just affect pain: COX play an important role in gut protection, blood clotting, kidney perfusion, and cardiovascular health. Popping NSAIDs triggers a domino effect that begins with suppressing pain and inflammation but ends with a cascade of unintended consequences.

Gastrointestinal issues

COX enzymes protect the stomach lining by promoting mucus and bicarbonate secretion. NSAIDs compromise this, damaging the stomach lining and potentially leading to irritation, ulceration, and bleeding. In fact, a third of patients consuming NSAIDs complain of gastrointestinal (GI) issues, and up to 70% of those taking them long-term have severe GI side effects (1). Don’t forget that exercise also strains the GI tract by forcing it to compete with muscles for limited blood supply. This increases the chances of GI upset, which is a common reason for DNFs during marathon and ultra-marathon. In fact, athletes who take NSAIDs before a marathon may be more likely to withdraw due to GI complaints.

Kidney stress

Strenuous exercise puts considerable stress on the renal system. Dehydration, electrolyte imbalances, and high core temperatures - all common issues in endurance sport - increase load on the kidneys. At the same time, the kidneys must filter out metabolic waste, including muscle metabolites and myoglobin that may leak into the blood due to muscle damage. During competition, the kidneys are already in a precarious position. NSAIDs make matters worse by further reducing renal blood flow through COX inhibition. Taking NSAIDs pre- or mid-race is like sucker-punching your kidneys when they’re already on the ropes, significantly increasing the risk of acute kidney injury.

Cardiovascular risks

No body system works in isolation, least of all the kidneys. The cardio-renal axis refers to the interconnectedness between the kidneys and the heart. It means that damage to one organ can affect the other in myriad ways. If the kidneys are over-taxed, excess fluid accumulates in the body, raising blood pressure and straining the heart. If the heart cannot adjust to the volume overload, fluid can build up in the lungs, potentially leading to a serious condition called pulmonary oedema. Inhibiting COX enzymes and prostaglandins by taking NSAIDs causes sodium and water retention, which further exacerbates blood pressure, forcing the heart to work harder. It all raises the chances of myocardial injury.

In a study of nearly 4,000 marathon runners, those who took aspirin or ibuprofen before the race were more likely to suffer adverse events including three who were hospitalised for kidney failure, four for GI bleeds, and two for cardiac infarctions (4). And a report from the 100-mile Western States race found that runners who had simultaneous rhabdomyolysis and hyponatremia were more likely to have used NSAIDs (5). These runners invariably had kidney damage and serious cardiopulmonary complications, requiring dialysis and extended hospital stays. Endurance exercise strains the body and challenges homeostasis in multiple ways. NSAIDs exacerbate the risks tenfold.

Endurance exercise strains the body and challenges homeostasis in multiple ways. NSAIDs exacerbate the risks tenfold.

Alternatives to NSAIDs

If you're looking for pain relief or inflammation control around exercise, there are safer, albeit perhaps less potent, alternatives to NSAIDs. Topical NSAIDs like diclofenac (the active ingredient in Voltarol) can be applied directly to painful muscles and joints, targeting the site of discomfort while minimising systemic absorption. This reduces (although doesn’t eliminate) the risk of gastrointestinal, renal, or cardiovascular side effects associated with oral NSAIDs (3).

Cold therapy remains a low-tech but effective option. Ice can help blunt peripheral pain signals and reduce local inflammation, though repeated application is needed to sustain the effect. And while it won't accelerate recovery, it may improve comfort enough to allow light activity.

Then there’s cannabidiol, or CBD, the wellness industry’s latest cash cow. CBD is widely promoted for pain relief, inflammation, and recovery, often added to balms, roll-ons, or oils. But despite the hype, most of the evidence is weak or inconsistent (see a previous blog on CBD). Where benefits are reported, placebo effects likely play a major role. And there's another wrinkle: many CBD products are poorly regulated. An impure formula may contain undisclosed or variable levels of THC (the psychoactive compound in cannabis that's banned in sport). So, you might be smearing your quads with a placebo if you’re lucky and a banned substance if you’re not. You have been warned.

Summary

Just over a decade ago, up to 93% of endurance runners were naïve to the contraindications of NSAIDs (4). I sincerely hope that’s an outdated statistic. Education on the risks is, therefore, crucial. All medical interventions - drugs, procedures, and devices - come with risks, and health professionals are trained to carefully balance the risks against the rewards. Increasingly, though, experts are concluding that the risks of NSAIDs are not justified by the benefits. Nowhere is this more apparent than during endurance exercise, when the kidneys are already under considerable strain.

Given the potential harm of NSAIDs, WADA might consider changing their status. After all, drugs aren’t banned only because they violate the spirit of fair play, but also because they’re unsafe. The growing body of evidence suggests that NSAIDs fit this description. Endurance racing is already a war of attrition. And while NSAIDs might help you transiently ignore pain, they also increase your chances of a DNF, or worse, a visit to A&E. During exercise, NSAIDs add fuel to the fire. Don’t get burned.

References

1. Tai FWD, McAlindon ME. Non-steroidal anti-inflammatory drugs and the gastrointestinal tract. Clin Med. 2021;21(2):131-134. doi:10.7861/clinmed.2021-0039

2. Robach P, Trebes G, Buisson C, et al. Prevalence of Drug Use in Ultraendurance Athletes. Med Sci Sports Exerc. 2024;56(5):828-838. doi:10.1249/MSS.0000000000003374

3. Derry S, Conaghan P, Silva JAPD, Wiffen PJ, Moore RA. Topical NSAIDs for chronic musculoskeletal pain in adults - Derry, S - 2016 | Cochrane Library. Accessed May 24, 2025. https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD007400.pub3/full

4. Küster M, Renner B, Oppel P, Niederweis U, Brune K. Consumption of analgesics before a marathon and the incidence of cardiovascular, gastrointestinal and renal problems: a cohort study. BMJ Open. 2013;3(4):e002090. doi:10.1136/bmjopen-2012-002090

5. Pasternak AV, Newkirk-Thompson C, Howard JH, Onate JC, Hew-Butler T. Four Cases of Acute Kidney Injury Requiring Dialysis in Ultramarathoners. Wilderness Environ Med. Published online February 15, 2023:S1080-6032(22)00219-8. doi:10.1016/j.wem.2022.12.004