The older children fared slightly better with an increased risk of 43 percent in those who took the drug more than once a year, but less than once a month. For those who took acetaminophen more than once a month, the risk of having asthma increased by 2.5 times, according to the report.
McBride calculated that if acetaminophen exposure was eliminated in that teen group, the rate of severe asthma symptoms would decline by 43 percent.
He also reviewed a meta-analysis of six studies involving almost 90,000 adults in total. Weekly use of acetaminophen was linked to a 1.74 times higher risk of asthma in adults, McBride found.
In addition, the researcher looked at two prospective studies done on acetaminophen and asthma in the early 1990s. These studies, which followed a group of individuals for a period of time, also found a strong link between asthma and acetaminophen.
McBride said the evidence is stronger that acetaminophen exacerbates current asthma, but that there's also evidence that it may be a cause of asthma, too.
How this occurs remains subject to debate, but some researchers believe acetaminophen increases airway inflammation in people with asthma or a predisposition to the breathing disorder, he said.
Dr. Len Horovitz, an internist and pulmonary specialist at Lenox Hill Hospital in New York City, said, "This information suggests that we have to be cautious about acetaminophen in children with asthma or a family history of asthma. The alternative is ibuprofen, which a lot of parents seem to prefer anyway."
"I do think further research is needed," Horovitz added.
He cautioned that a small group of people with asthma are sensitive to aspirin, and said there are some others who have nasal polyps who shouldn't take ibuprofen (Advil, Motrin).
Not everyone is convinced that the association seen in the new study leads to cause and effect.
"Asthma is such a complex disease,
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