Use of acetaminophen can lead to the development of asthma and eczema, Science Daily reports in their article Acetaminophen Use in Adolescents Linked to Doubled Risk of Asthma. Monthly use of the drug was linked to more than a double risk of asthma and eczema; while yearly use was associated with a 50 percent increase in the risk of asthma.

Study first author Richard Beasley, M.D., professor of medicine at the Medical Research Institute of New Zealand on behalf of the International Study of Asthma and Allergies in Childhood (ISAAC) says, ‘This study has identified that the reported use of acetaminophen in 13- and 14-year-old adolescent children was associated with an exposure-dependent increased risk of asthma symptoms.’ The research will be published online on the American Thoracic Society's website, followed by publication in the American Journal of Respiratory and Critical Care Medicine.

More than 300,000 13- and 14-year old children in 113 ISAAC centers throughout 50 countries participated in the study. They were given two written questionnaires and one video questionnaire, which asked them to quantify their acetaminophen use as well as their asthma, eczema, and allergy symptoms.

Researchers discovered a significant association between acetaminophen use and the risk of asthma and eczema: 43 percent higher in medium users (at least once in the last year) and 2.51 times the risk in high users (at least once in the last month). Allergic nasal congestion was also linked to acetaminophen use: 38 percent higher for medium users and 2.39 times greater for high users. Eczema risk was 31 percent and 99 percent higher in medium and high users.

While a causal link could not be definitely determined because of the way the study was conducted, evidence gained from other studies does suggest such a link. Biologically, acetaminophen may have a systemic inflammatory effect that leads to enhanced allergic immune responses. In addition, the drug may suppress the immune response to and prolong the symptomatic illness from colds, leading to asthma exacerbation.

Dr. Beasley points out that ‘if the associations were causal, they would be of major public health significance’ and that ‘randomized controlled trials are now urgently required to investigate this relationship further and to guide the use of antipyretics, not only in children but in pregnancy and adult life.’