Background: Epidemiologic studies have identified an increased risk of asthma with acetaminophen use, but the results have been conflicting. We sought to quantify the association between acetaminophen use and the risk of asthma in children and adults.
Methods: We searched all the major medical databases, including MEDLINE (from 1966 to 2008) and EMBASE (from 1980 to 2008) to identify pertinent articles. All clinical trials and observational studies were considered. For observational studies, we selected those that clearly defined acetaminophen use and asthma diagnosis. Study quality was assessed by two reviewers, and data were extracted into a spreadsheet. A random-effects model was used to combine studies with asthma and wheezing among both children and adults.
Results: Thirteen cross-sectional studies, four cohort studies, and two case-control studies comprising 425,140 subjects were included in the review. The pooled odds ratio (OR) for asthma among subjects using acetaminophen was 1.63 (95% CI, 1.46 to 1.77). The risk of asthma in children among users of acetaminophen in the year prior to asthma diagnosis and within the first year of life was elevated (OR: 1.60 [95% CI, 1.48 to 1.74] and 1.47 [95% CI, 1.36 to 1.56], respectively). Only one study reported the association between high acetaminophen dose and asthma in children (OR, 3.23; 95% CI, 2.9 to 3.6). There was an increase in the risk of asthma and wheezing with prenatal use of acetaminophen (OR: 1.28 [95% CI, 1.16 to 41] and 1.50 [95% CI, 1.10 to 2.05], respectively).
Conclusions: The results of our review are consistent with an increase in the risk of asthma and wheezing in both children and adults exposed to acetaminophen. Future studies are needed to confirm these results.