Original Articles By Dr. Lavin Featuring Expert Advice & Information about Pediatric Health Issues that you Care the Most About

This Time the Update Is on Acetaminophen: As We Approach Cold, Flu, and COVID-19 Season, There Is More Reason Not to Take Tylenol

By Dr. Arthur Lavin

Perhaps one of the most common drugs used in childhood is acetaminophen, whose most common brand name in the United States is Tylenol.

Readers of Real Answers may recall our original post raising concerns about the use of acetaminophen ten years ago- https://www.advancedped.com/another-worry-tylenol-acetaminophen/

This post looked at the history of use of acetaminophen, its relation to other medications that have caused harm to kidney function, the known toxicity in overdose situations of  acetaminophen to the liver, and emerging indications that use of  acetaminophen in childhood may be related to increased risk of developing asthma in childhood.

And more recently, in 2017, a study was published which showed a rather striking association between use of  acetaminophen during pregnancy, and the chance a child born would later develop asthma.  https://www.advancedped.com/another-worry-tylenol-acetaminophen/

Now we have received further information from some of the world’s epidemiologists on both concerns, namely, the risk of a child taking acetaminophen suffering increased chances of developing asthma, and the impact of exposure to  acetaminophen during fetal life on later brain function and reproductive function.

Acetaminophen during Pregnancy

This is a complex subject since NSAIDs, such as ibuprofen (Motrin, Advil) cannot be taken during pregnancy at all.  If it turns out that  acetaminophen cannot be taken, that severely limits the ability of pregnant women to take pain and fever relief, a serious problem.   As a result, formal recommendations to not take  acetaminophen during pregnancy have not been issued by the leading OB/GYN professional society, the American College of OB/GYN (ACOG).

Still, it is important for everyone to be aware of the basis of concerns being raised.  They fall into two realms- the function of the developing baby’s reproductive system, and of the baby’s brain.

The evidence for acetaminophen causing harm to the development of the reproductive system is based on the results of a number of studies that link use of acetaminophen for more than 2 weeks, and during a critical period, namely the end of the first trimester to the second trimester.  Most of the impact on the reproductive tract appears to be related to male development with potential for increased risk of genital tract anomalies and decreased fertility.  Some animal studies show trends of decreased egg production in the ovaries subsequent to end of first trimester and second trimester exposure as well.

The evidence for acetaminophen causing harm to fetal brain development comes from 26 studies that looked at a total of over 200,000 mother-child pairs from around the world.  Of these studies, 22 of 26 found evidence that prenatal exposure to acetaminophen can impair subsequent brain function.  A wide range of brain dysfunctions were found to be more common if the fetus was exposed to acetaminophen.  The most common was the one mentioned in our 2017 post, ADHD.  But others are now known as well, including: behavioral abnormalities,  autism, language delays, lower IQ, cerebral palsy, oppositional-defiant disorder, poorer executive function, and conduct disorders.

Acetaminophen use in Childhood and Asthma

Discussion with some of these epidemiologists confirms that the evidence for use of acetaminophen in childhood is related to increased risk for developing asthma has only become more convincing over time, and is now widely accepted by epidemiologists.  The  acetaminophen used, the higher the risk of developing asthma in childhood.

One danger for use of acetaminophen that is solidly proven only appears in overdose situations, but is relevant to these considerations.  If anyone at any age takes enough acetaminophen, it will not just harm, but destroy your liver.   And, many authorities also are concerned about the impact of use of  acetaminophen on kidney function.  These points relate to the fact that a drug closely related to acetaminophen is a known toxin to kidneys.  And, lungs, livers and kidneys all develop from similar tissue layers in the embryo.  The patterns raise the plausibility for  acetaminophen causing the increased risk for asthma.


  1. When questions are raised about medications that we have decades of trust established, and that are nearly universally used, those questions need to be raised very carefully.
  2. There are few drugs used in childhood as often as acetaminophen.  And on the surface, used at the right dosage, there are few stories of any harm occurring, it appears to be quite safe.
  3. Some dangers, however, are hard to see in one’s home.  Let’s say a common drug increased the chance of a problem that happens to 5 in 100 children to go to 7 in 100 children?  How would anyone in a single family know?  The answer is that no one would know.  But if that happened there would be about 40% more children with that problem if allowed to continue use.
  4. We still do not have enough proof to say for sure that use of acetaminophen will cause a certain amount of harm.  At the same time, the evidence raises enough questions, that we at Advanced Pediatrics continue to advise that children use ibuprofen for their pain and fever needs and not use acetaminophen unless really necessary.
  5. The case for acetaminophen potentially causing harm falls into three main categories.
  6. Prior to birth, particularly at the end of the first trimester and second trimester there may be increased chance of harm to the reproductive function of the male and even female baby-to-be.
  7. Prior to birth, particularly at the end of the first trimester and second trimester there may be increased chance of harm to the brain of the baby-to-be leading to increased chance of a wide range of brain functions.
  8. During childhood, the question of whether acetaminophen increases the chance of developing asthma remains a serious possibility that has only grown more plausible and likely over the last 10 years.

Acetaminophen is a very popular medication.

At the same time, it is far from essential during childhood.  Ibuprofen is more effective than acetaminophen in reducing fever, adding acetaminophen to ibuprofen during fevers only offers a bit more relief, and acetaminophen has very limited anti-inflammatory powers.

Given that ibuprofen works as well if not better, and that serious questions continue to grow about use of acetaminophen in children, we are repeating our recommendation that parents not give their children acetaminophen unless a brief course becomes truly necessary.

For pregnant women, the evidence suggests that avoidance of acetaminophen, when feasible, particularly for uses over 2 weeks, and near the end of the first, and the second trimester would be prudent as the evidence is sorted out.

As we approach the viral time of year, this fall, we offer this advice to make sure keeping comfy is as safe as possible.

To your health,
Dr. Arthur Lavin


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