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0837 Does paracetamol cause asthma?
One would have thought that 205 847 questionnaires in which parents of 6-7 and 13-14 year-olds were asked about paracetamol use in the first year of life and subsequent development of asthma would be sufficient to answer whether paracetamol causes asthma in subsequent years. This large sample covered 73 centres in 31 countries, and the authors of the article recently published in the Lancet found that a) paracetamol use in the first year correlated strongly with asthma symptoms at 6-7 years; b) current use of paracetamol was associated with a dose-dependent increased risk of asthma symptoms; c) there was a correlation between paracetamol use and rhinitis and eczema. These are not altogether new findings: previous data from the European Union have also shown a positive association between per-person paracetamol consumption and asthma. If there is indeed a causal relationship then the mechanism could be via depletion of glutathione and glutathione-dependent enzymes, which would reduce the body’s ability to withstand oxidative stress. Under these circumstances, reactive oxygen species generation resulting from allergic, viral or other non-allergic stimuli could produce or enhance inflammation, which in turn could lead to development or worsening of pre-existing asthma, rhinoconjunctivitis or eczema. Low glutathione may also alter T-helper cell pathways in terms of antigen presentation and recognition, thereby favouring the T-helper-cell-2 pathway. These effects occur even with therapeutic doses of paracetamol. Reasons for not accepting the data as definitive and sufficient to recommend paracetamol avoidance in asthma guidelines include the possibility that more paracetamol is given to asthmatics than to non-asthmatics, and there may be recall bias amongst parents of asthmatics. Bottom line: despite these highly suggestive findings, further prospective research is required, including randomized controlled trials.
Read more:
Lancet 2008; 372: 1039-48 and 1011-12
Chest 2005; 127: 604-12
J Allerg Clin Immunol 2005; 116: 859-62 |