Hello ThereNov. 5, 2009 — The popular pain and fever reliever acetaminophen may be linked with an increased risk of asthma in children and adults, according to a new research review of previously published studies by Canadian researchers.

But the manufacturer of Tylenol — the brand-name version of acetaminophen — says the painkiller has a well-established safety record.

Researchers pooled the results of 19 clinical studies, with a total of more than 425,000 participants, to see if the association between the pain reliever use and asthma (and wheezing in children) held up. It did.

What triggered the review? “Concern over the risk of acetaminophen and asthma highlighted by the 2008 ISAAC study, published in The Lancet,” says the review’s lead author Mahyar Etminan, PharmD, a scientist at the Vancouver Coastal Health Research Institute in British Columbia and an assistant professor of medicine at the University of British Columbia.

In the ISAAC (International Study of Asthma and Allergies in Childhood) study, researchers looked at more than 205,000 children, ages 6 to 7, in 31 countries and found that acetaminophen use for fever in the first year of life was linked to increased risk of asthma symptoms in children 6 to 7 years old. Current use of acetaminophen was also linked to increased risk of asthma symptoms.

Other studies, Etminan says, have produced conflicting results, so the Canadian team conducted the review.

Sales of acetaminophen products in the U.S. are about $1 billion annually, the researchers estimate.

Calculating Asthma Risk

Etminan’s team searched the medical literature to find high-quality published studies, trying to quantify the risk of asthma and wheezing among acetaminophen users, as well as the effect of prenatal exposure to the medicine.

After eliminating studies that weren’t scientifically sound enough, the researchers focused on 19 studies. Overall, they found that acetaminophen users were 63% more likely to have asthma than nonusers. Other findings:

  • The risk of asthma in children given acetaminophen in the year before their asthma diagnosis was increased by 60%.
  • The risk of asthma in children who used acetaminophen in the first year of life was 47% higher than in those who didn’t use it.
  • The risk of asthma in adults who used acetaminophen was 74% higher than in those who did not.
  • Prenatal use of acetaminophen boosted the risk of wheezing by 50% and the risk of asthma by 28% in children.



Acetaminophen has been getting a lot of bad press lately. I’m not too surprised as the adverse effects have been well known which include: acute liver toxicity, allergic reactions including swelling, difficulty breathing, closing of throat, abdominal pain, nausea, unusual bleeding or bruising, and of course, death.

One of the important thing to remember is when you introduce an biochemical agent into the body that interrupts multiple chemical pathways throughout the body - not just the reduction of pain. Many of the pharmaceutical drugs lack specificity - meaning that they effect a cascade of biological processes which cause so-called “Side Effects”.

When it comes to treating arthritis, the first thing I recommend is reducing your intake of the Nightshade family of foods: Potatoes, Tomatoes, Eggplant, and Peppers. They have all been found to worse joint pain.

Using Tylenol to reduce fevers in children can have undesired consequences.

Creative Commons License photo credit: rumpleteaser

  • Acute liver toxicity
  • Allergic reactions including swelling, difficulty breathing, closing of throat, and more
  • Abdominal pain
  • Nausea
  • Unusual bleeding or bruising
  • Death



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