Tylenol Linked to Asthma?

When I was in elementary school, my best friend has asthma. I know this because he told me he had it. I never saw any symptoms, he was a great athlete with good endurance.
Today, it seems like everyone and their brother has asthma. The street wisdom on why we have more asthma in 2011 than 1981: kids are not as tough as they used to be. Eventually, I think science will show that there are other factors that have actually increased asthma, nut allergies, and the like.

Cue the suspects. Today’s suspect is Tylenol. It is one of those “everyone uses this at some point” products. Tylenol, known by its generic name acetaminophen, is a popular pain reliever and fever reducer. It is estimated that in any given week 23% of Americans use acetaminophen. Recent concerns regarding liver injury have been raised; however, other side effects such as asthma and eczema have also recently been gaining notice. The potential risk for asthma when administered to children and use during pregnancy is a concern that was first raised over 10 years ago.

Several studies have suggested that acetaminophen use in pregnancy, infancy, later childhood and adulthood may be associated with an increased prevalence of asthma. Two large observational studies have demonstrated that increased use of acetaminophen in children has occurred due to concerns of Reye’s Syndrome and allergy/asthma to aspirin or other NSAIDs (non-steroidal anti-inflammatory drugs).

A meta-analysis (Etminan et al., 2009) suggested that the risk (odds ratio) of acetaminophen associated asthma is 1.63 in children and adults and use during pregnancy lead to a risk of 1.28 for asthma and 1.50 for wheezing in children. An odds ratio of 1 means that asthma is likely to occur in both groups (those that used acetaminophen and those that didn’t, equally) and an odds ratio greater than 1 shows that asthma is more likely to occur with acetaminophen use than without. A follow-up study was conducted by Eyers et al. (2011) to build on these findings. These authors reported a risk for wheezing in children of 1.21 in offspring of women who used acetaminophen during pregnancy. This study provides further evidence of the relationship of acetaminophen use with asthma and wheezing in children. In a study reviewing use of high dose acetaminophen, it was found that the risk of asthma more than tripled.
As there are confounding factors that may also lend to the increased prevalence of asthma and respiratory disorders in children, it is interesting to note that there are many large population based studies which suggest the association of acetaminophen use increases risk of asthma and wheezing.

Further research is necessary to fully understand this relationship between acetaminophen use and respiratory conditions. I don’t think any lawsuits are imminent. There is still too much that science needs to do to sort this out.