We Don’t Know If Tylenol Can Cause Autism—and That Didn’t Change Last Monday

This commentary was adapted from episode 188 of the Health & Veritas podcast. The views expressed are the author’s own. Subscribe for weekly doses of expert insight on health and the healthcare industry.

The president’s news conference on September 22 was another moment when politics and populism seemed to trump science and the public’s interest.

There is uncertainty as to whether acetaminophen, the active ingredient in Tylenol, is a cause of some cases of autism spectrum disorder and/or attention deficit hyperactivity disorder. This uncertainty arises from the fact that we don’t do randomized trials in pregnant women and we therefore end up relying on various observational studies to identify a correlation—which is not necessarily a causation. With acetaminophen, there are studies that raise enough concern to be worthy of our attention.

It should be noted that the level of impact, if real, is likely very, very low. But low is still something to consider.

The complication in determining whether this effect is real is confounding factors: Are women taking acetaminophen for mostly random reasons and, therefore, a correlation with autism among these women is more likely causative? Or are they taking acetaminophen because they have migraines or high fevers or for some other specific reason, in which case other factors might be in play. Studies have tried to tease this out; but they can only do so much. The scientific consensus is that we don’t know the answer. And one of the best recent studies, which involves siblings in Sweden, comes to the opposite conclusion than the president and his healthcare staff did.

We must get better answers to this question. But my serious quarrel with this news conference is not that such information is wrong; it is that the guidance to women should be coming from trusted professionals and not from those who might be leveraging the anxiety of the public over growing counts of autism cases. (I say counts because it is unclear how much of the growth in autism is actually due to finding cases that were never identified in the past rather than an increase in the prevalence of the disorder because of genetic or environmental factors.) We should absolutely be searching for answers, and then providing them with deliberateness, thoughtfulness, and compassion. We should not be using this issue to score political points.

We should all consider that what we put in our bodies has some risk of untoward effects. Acetaminophen may be an over-the-counter medication, but it is not without its own risks; recent changes to labelling remind us that lower total consumption is safer. So we should always advise patients to take the lowest amount of a medication that will satisfactorily resolve symptoms for them, under the guidance of their physician or nurse practitioner. There are no other pain or fever remedies that are safe for pregnant women; if there were, we would be having a different conversation.

We should also remember that there have been numerous medical fakeouts over the last century. We once thought ulcers were caused by stress; that hormone replacement therapy reduced the risk of heart disease; that AIDS was caused by environmental factors; that vitamin E was cardioprotective; that beta-carotene protects against lung cancer; and that tonsillectomy was protective against future infections. All of these ideas have, to one degree or another, been disproven; occasionally, the opposite has proven to be correct. This is why we don’t jump the gun on science, or at least try not to.

Mothers of neurodivergent children may start to blame themselves for causing differences in their children. It is important for them to understand that the weight of the evidence is strongly against this hypothesis. For women who are currently pregnant, talk to your ob-gyn or primary care provider to make the best decisions for you and your fetus. Suffering in pain or with fever may also be harmful to the fetus, so please seek advice.