New study of the potential acetaminophen/asthma link

Published Online: October 28, 2014

The prevalence of childhood asthma has risen dramatically since the 1980s. During this same time period there was also a substantial increase in the use of acetaminophen and ibuprofen to treat fever (as alternatives to aspirin, which had been linked Reye’s syndrome).  Many of the original studies examining the relationship between antipyretics (fever-reducing medications) and asthma found that acetaminophen was associated with higher asthma risk. However, these studies often failed to account for the indications that prompted the use of antipyretics, raising the question of whether the over-the-counter medications, or the underlying infections themselves, are truly associated with asthma.  

In a study recently published in The Journal of Allergy and Clinical Immunology, J. Sordillo and colleagues investigate the association of anti-pyretic intake 1) during pregnancy 2) during the first year of life (infancy), with asthma-related outcomes, both before and after controlling for early life respiratory infections. The authors adjusted their analysis for early life respiratory infections because they are a common indication for antipyretic use, as well as an independent risk factor for asthma. The study included 1490 mother-child pairs in Project Viva, a longitudinal pre-birth cohort. Prenatal acetaminophen exposure was categorized as the maximum intake (never, 1-9 or ≥ 10 times) in early or mid-pregnancy, and ibuprofen intake as presence or absence in early pregnancy. Antipyretic intakes in infancy were expressed as never, 1-5, 6-10, or >10 times. The study examined associations of acetaminophen and ibuprofen (per unit increase in exposure category) during pregnancy and infancy with wheeze, asthma and allergen sensitization in early (3-5 y) and mid-childhood (7-10 y).

Unadjusted analyses showed an increased risk of asthma (both in early and mid-childhood) for infants with higher intakes of acetaminophen and ibuprofen in early life. After controlling for respiratory infections, risk estimates were substantially diminished (particularly for the early childhood outcome), suggesting that underlying respiratory infections may drive the association between antipyretic intake and asthma. While the author’s analyses did show a potential link between prenatal exposure to acetaminophen and asthma outcomes in early childhood, these associations did not persist in models for mid-childhood asthma. Further studies with detailed information on timing and dose of antipyretics during pregnancy, as well as maternal indication for antipyretic use are required to better understand these relationships.

The Journal of Allergy and Clinical Immunology (JACI) is an official scientific journal of the AAAAI, and is the most-cited journal in the field of allergy and clinical immunology.

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