People usually have good reasons for swallowing over-the-counter painkillers: They're hurting.
But though the drugs often help, new research suggests that they sometimes do the opposite of what their users intended. That's especially true for serious athletes, for whom pain — and painkillers — are regular companions.
In recent years, scientists have been studying runners competing in the Western States Endurance Run, a 100-mile race through California's Sierra Nevada mountains that involves more than 18,000 total feet of uphill climbing, more than 21,000 feet of downhill running and an average of 26 hours to complete. After some initial surveys, the researchers learned that 7 out of 10 of the runners regularly took ibuprofen — by far their drug of choice — during training. Many took up to three times the maximum daily dose to get through the pain of the race.
To learn whether the drug was doing the ultra-runners any good, the original plan was to randomly assign some to take ibuprofen and others to abstain during both training and racing, says lead author David Nieman, director of the Human Performance Lab at Appalachian State University in Boone, N.C. But use of the drug was so widespread and the runners felt so dependent on it that the medical board thought it would be unethical to ask them not to take it during training.
One of Nieman's studies instead looked at more than 50 runners, all of whom took ibuprofen regularly leading up to the race. About half of the athletes took a 600 milligram dose of ibuprofen the day before the race and then 1,200 mg on race day — a 200 mg tablet about once every four hours. The other group of runners remained drug-free from the day before the race until a week later.
The researchers performed blood and urine tests. The results were striking.
After the race, runners who had taken ibuprofen showed signs of mild kidney impairment as well as mild endotoxemia, a potentially dangerous condition in which bacterial toxins present in the large intestine get into the bloodstream, Nieman and colleagues reported in 2006 in the journal Brain, Behavior and Immunity.
The drug also failed to help performance or recovery, the researchers reported in that paper and others. Both groups of runners reported equivalent amounts of pain during the race. Their times were the same. And afterward, their muscles were equally sore.
Most ironic, runners on ibuprofen actually had 50% more inflammation in their bodies after the race, even though athletes often choose to take the drug to fight inflammation.
Scientists don't yet know whether ibuprofen or other nonsteroidal anti-inflammatory painkillers (NSAIDs) have the same negative consequences in more moderate exercisers. But there is cause for concern, Nieman says.
Animal research suggests that a rise in body temperature during exercise gives ibuprofen a chance to damage cells in the colon and kidneys, he says. And human studies have shown that people who regularly exercise and take ibuprofen have elevated levels of endotoxemia.
"I think there's no safe time for exercisers to take ibuprofen," Nieman says. "Until we know more, I tell athletes, 'Don't use it.' More than anything, it just doesn't work."
Taking over-the-counter painkillers can sometimes backfire for other groups too, including people who get migraines.
On the plus side, studies have shown that all four over-the-counter drugs can help treat these pounding headaches, says neurologist Peter Goadsby, director of the Headache Program at UC San Francisco. Doctors tend to recommend naproxen first because it is the longest acting of the NSAIDs — a good strategy for migraines, which can last for days.
Over time, though, excessive use of painkillers — especially acetaminophen — can lead to rebound headaches, which come back as soon as the drug wears off. As medicines seem to become less and less effective, people become more and more dependent on their ability to self-medicate, and the risks for overdosing grow.
To avoid rebound headaches, doctors warn against taking acetaminophen for migraines more than 15 days a month — and suggest discussing options for other treatment strategies instead.