A major new international study released Friday has found that adolescents who take acetaminophen, better known under the brand name Tylenol, have a higher risk of asthma, allergic nasal conditions and the skin disorder eczema.

Those who took the common painkiller as infrequently as once a month had twice the normal risk of developing the disorders. Experts noted, however, that the study does not show that the drug causes the problems. In fact, some said, it is equally likely that the children were taking the drug because they were already suffering from asthma.

Acetaminophen is widely viewed as a very safe drug-one reason why hospitals use it routinely as a painkiller instead of aspirin or ibuprofen. The major problem associated with it is liver damage caused by overdoses. Recently, however, there has been a growing drumbeat about possible dangers from the drug. One study, for example, found that acetaminophen increased the risk of hearing loss in men. And some others have hinted that the drug is linked to asthma in newborns whose mothers used the drug during pregnancy and in young children exposed to it.

The new findings were reported in the American Journal of Respiratory and Critical Care Medicine by researchers […]