NEW YORK (Reuters Health) - Swiss researchers have tied asthma risk to several common painkillers, adding to ongoing controversy about the role of such drugs in the worldwide upswing in the disease.
But they say their work hints that painkillers aren't at the root of the problem, but rather a consequence of it.
Earlier studies have found that kids who commonly take acetaminophen, a leading painkiller sold as Tylenol in the U.S., are more likely to develop wheezing and other symptoms of asthma.
What is not clear is whether acetaminophen triggers asthma directly or is simply used more often by kids whose lungs are prone to infections from the get-go. (See Reuters Health stories of August 13 and October 13, 2010.)
"If we thought it could really cause asthma, the next step would be to change prescriptions," said Dr. Claudia Kuehni of the University of Berne in Switzerland, who led the new study.
She said her findings, which at first glance may seem to confirm that painkillers can harm the airways, actually appear to acquit the drugs, including acetaminophen.
The researchers tapped into data from more than 1,000 young adults who had survived childhood cancer and were mostly well. Over two years, seven percent reported asthma attacks or use of asthma medication, which is similar to rates in the general population.
About four percent of people who said they hadn't taken painkillers had asthma, while the rates were more than twice as high among those who used the drugs.
Both acetaminophen and drugs such as ibuprofen (Advil) and naproxen (Aleve) -- so-called nonsteroidal anti-inflammatory drugs, or NSAIDs -- were tied to increased asthma risks. This wasn't true for aspirin, however, most likely because it isn't recommended for asthmatics, Kuehni said.
While the results don't say anything about cause and effect, they do hint that painkillers are the result, not the cause, of airway disease, according to the researchers, whose study appears in the Journal of Allergy and Clinical Immunology.
"Children who have asthma have more severe respiratory infections with fever and so tend to use more acetaminophen," Kuehni told Reuters Health.
"Based on these data there is no suggestion that we have to change prescriptions," she said, adding that the results should reassure parents about the safety of painkillers.
Still, she advised that children use the drugs as little as possible. Aspirin is usually not recommended because it can cause short-term breathing problems and other rare side effects.
But studies like the current one can't settle the question finally, experts say; for that, large trials that randomly assign children to different painkillers are needed, Dr. Richard W. Beasley, of the Medical Research Institute of New Zealand, told Reuters Health earlier this year.
"Only then will it be possible to determine the role of acetaminophen in the causation of asthma and to formulate evidence-based guidelines for the optimal use of acetaminophen," he said in an e-mail.
SOURCE: The Journal of Allergy and Clinical Immunology, online November 19, 2010.