Overall trends in asthma prevalence also suggest a link between acetaminophen and asthma, Dr. Nelson says.
“The onset of the so-called asthma epidemic in the U.S. was in 1980, and that is about the time that aspirin was recognized as probable cause for Reye syndrome,” he says, referring to a potentially fatal disease affecting the brain and liver. “Cases of pediatric asthma went up when aspirin use went down.”
It’s unclear how acetaminophen might influence asthma symptoms. Some experts believe the drug may suppress the immune system and cause body-wide inflammation. (Asthma is a condition in which lung airways are chronically inflamed.)
Neil Schachter, MD, a professor of pulmonary and community medicine at Mount Sinai Medical Center, in New York City, says that the acetaminophen-asthma link is a chicken-or-egg question. Children with asthma might be more likely to take acetaminophen, rather than vice versa, he points out.
“We know that kids with asthma get sick a lot, and they are prescribed a lot of combination medications which contain acetaminophen, so that makes it more likely that children with asthma will use Tylenol in general,” he says.
The teenagers in the study were simply surveyed about how often they took acetaminophen and their history of asthma, eczema, or other allergy symptoms, so it’s possible that medications besides acetaminophen—or other, unrelated factors—could explain much of the link seen in the study.
Aspirin and nonsteroidal anti-inflammatory drugs (NSAIDs) have also been linked to an increased risk of asthma, Dr. Schacter says. These drugs can trigger the production of leukotrienes, a naturally occurring chemical substance that promotes an inflammatory response in the lungs.
“The implications that aspirin, NSAIDs, and now Tylenol increase asthma risk doesn’t leave a whole lot of anti-fever or analgesic drugs to treat children who get sick all the time,” he says. “Talk to your doctor or child’s pediatrician before making any changes.”
