The effects of early and late paracetamol exposure on asthma and atopy: a birth cohort

P>Background Despite reports of positive associations between paracetamol and asthma, the nature of these associations is unclear. Objective We aimed to investigate the associations between infant and childhood paracetamol use and atopy and allergic disease at 5-6 years. Methods In a birth cohort study, we collected reported paracetamol exposure between birth and 15 months in Christchurch (n=505) and between 5 and 6 years for all participants (Christchurch and Wellington) (n=914). Outcome data for reported current asthma, reported wheeze and atopy (measured using skin prick tests) were collected at 6 years for all participants. Logistic regression models were adjusted for potential confounders, including the number of chest infections and antibiotic use. Results Paracetamol exposure before the age of 15 months was associated with atopy at 6 years [adjusted odds ratio (OR)=3.61, 95% confidence interval (CI) 1.33-9.77]. Paracetamol exposure between 5 and 6 years showed dose-dependent associations with reported wheeze and current asthma but there was no association with atopy. Compared with use 0-2 times, the adjusted OR (95% CI) were wheeze 1.83 (1.04-3.23) for use 3-10 times, and 2.30 (1.28-4.16) for use > 10 times: current asthma 1.63 (0.92-2.89) for use 3-10 times and 2.16 (1.19-3.92) for use > 10 times: atopy 0.96 (0.59-1.56) for use 3-10 times, and 1.05 (0.62-1.77) for use > 10 times. Conclusion and Clinical Relevance Our findings suggest that paracetamol has a role in the development of atopy, and the maintenance of asthma symptoms. Before recommendations for clinical practice can be made, randomized-controlled trials are needed to determine whether these associations are causal.