In recent months, several news stories have been published that indicate there appears to be a link between acetaminophen and asthma. Experts call this a "risk factor." So does this mean you should stop taking Tylenol (or other acetaminophen brands) if you have asthma? Not necessarily...
What We DO Know
There are many different known risk factors for asthma, including environment, heredity and exposure to certain allergens or irritants. But researchers are anxious to learn as much as they can about asthma because there has been such rapid growth in the numbers of people with asthma over the last couple of decades. These experts want to know why, because with such knowledge may come a cure for asthma or at least better prevention.
Acetaminophen lowers the level of a substance called glutathione, which is an antioxidant, that is found in lung tissue. Antioxidants help fend off inflammation. Inflammation is at the root of most asthma symptoms, particularly allergic-type asthma.
Also, a large study published in 2008 that interviewed patients who had asthma suggested that taking acetaminophen increased the risk of wheezing and asthma. The study relied on what people had to say, though, not scientific testing.
What We Don't Know
Unfortunately, experts don't really know for sure why one person will get asthma, while another one with a similar background or lifestyle will not. While we know what at least some of the risk factors for asthma are, being exposed to these risks is no guarantee that you will definitely get asthma.
We also know that inflammation in the airways is the result of the body's overreaction in people with asthma to certain things that are normally harmless to other people, such as dust and pollen. But we don't know for sure why people with asthma experience this. It appears to be some kind of malfunction in the immune system.
The Recent Study
Because of the 2008 study mentioned above, a Dr. J. Mark FitzGerald and his associates from the Vancouver Coastal Health Research Institute in British Columbia decided to look into the connection between acetaminophen and asthma a bit further. To do so, they examined the results of 19 previous studies, involving 425,140 patients.
This type of retrospective study isn't the best way to prove anything. It is used more to find stronger evidence that further study of an issue is needed.
What Dr. FitzGerald found was that people who took acetaminophen seemed to be 1.6 times as likely to develop asthma. Even children whose mothers took Tylenol when pregnant had 1.3 times more risk of getting asthma. Kids who took high doses of asthma were 3 times as likely to develop asthma.
So it definitely seems that there may be a link between acetaminophen and asthma and more study is needed to understand that link. But it's important to understand that it is only one risk factor, and not a direct cause. Not every person who takes a couple of Tylenol should worry that they are going to end up with asthma.