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Taking painkillers before a marathon may be harmful

Taking diclofenac, ibuprofen, and other common painkillers before running a marathon could increase the risk of gastrointestinal cramping, bleeding, and other problems, a study suggests.

BMJ Group News

What do we know already?


Endurance sports such as marathons are, by nature, hard on the body. To prevent some of the aches and pains that go along with this type of extreme activity, many people take pain medicine before they race.

Many common painkillers - including diclofenac, ibuprofen, and aspirin - work by slowing down the body’s production of an enzyme called cyclo-oxygenase. This can reduce pain and swelling, but it can potentially harm other parts of the body, including the kidneys, stomach, and heart. These drugs are usually safe when taken at regular doses and under normal circumstances. But what about when the body is under the stress of a high-endurance activity?

Researchers looked at questionnaires filled out by 3,913 runners in the 2010 Bonn Marathon about their use of painkillers before the race, any problems they had during or after, and whether they had to drop out.

What does the new study say?

Nearly half of those who returned the questionnaire - 49 in 100 people - said they took painkillers before the race. The most common medicine was diclofenac, followed by ibuprofen, then aspirin, and then paracetamol and other medicines combined.

People who took painkillers were much more likely to have had a problem during or after the race, with 16 in 100 reporting a problem compared with 4 in 100 people who didn’t take pain medicine. The most common problems were:

  • Gastrointestinal cramping. This affected 14 in 100 people taking pain medicine, compared with less than 1 in 100 not taking these drugs.
  • Heart and circulation problems. This was reported by 9 in 100 people taking painkillers, compared with 3 in 100 people not taking them.
  • Gastrointestinal bleeding or blood in the urine. Each of these problems affected nearly 4 in 100 people taking pain medicine. Among people not taking these drugs, no one reported blood in their urine and only a few reported gastrointestinal bleeding.

The researchers estimated that, for every eight people who took painkillers before a race, one would be harmed. The chance of problems was higher if people took larger doses of painkillers, or if they ran a full marathon rather than a half marathon.

The percentage of people who withdrew from the race because of pain was the same in both groups, suggesting that taking painkillers ahead of time didn’t help in this respect. In fact, joint and muscle pain after the race were more common in people who had taken painkillers.

How reliable is the research?

Although these results may seem conclusive, there are a few things to remember. Having people voluntarily fill in questionnaires isn’t a very reliable way to do research, for several reasons. For example, people who had problems during or after the race might have been more likely to complete the questionnaire than other participants, or vice versa.

The researchers also didn’t know anything about the runners’ medical histories, so they didn’t know whether some people might have been more likely than others to have problems, with or without painkillers. We do know that people who took pain medicine were older, on average, than those who didn’t take these drugs. This might have increased their chance of having problems.

What does this mean for me?

If you run marathons, these findings suggest that taking pain medicine before a race could be harmful. Although we need better-quality studies to confirm these findings, we do know that pain medicines carry risks, and other studies suggest intense physical activity may increase the chance of problems.

Published on April 20, 2013

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