Doctors Told Pregnant Women Tylenol Was Safe – New Research Raises Doubts

A new study suggests that fetal exposure to acetaminophen significantly increases the risk of ADHD in children, raising concerns about its safety during pregnancy.

While acetaminophen has long been considered a low-risk pain reliever for pregnant women, this research—tracking a cohort of over 300 mothers—found that children exposed to the drug had nearly double the likelihood of developing ADHD. The effect was even more pronounced in girls, though researchers are unsure why.

Acetaminophen in Pregnancy: A Hidden Risk?

A new study published in Nature Mental Health suggests that fetal exposure to acetaminophen may increase the risk of ADHD in children.

Acetaminophen, the active ingredient in many pain relievers such as Tylenol and NyQuil, is commonly used during pregnancy. Research shows that up to 70% of pregnant women take it to relieve pain or reduce fever. The U.S. Food and Drug Administration (FDA) has long considered it one of the few safe medications for pregnancy.

Should Doctors Reconsider Acetaminophen?

However, the study’s findings suggest that doctors may need to reconsider its use during pregnancy.

“Most of the prior studies asked women to self-report whether they had taken Tylenol or anything that contained acetaminophen,” said lead author Brennan Baker, a researcher at Seattle Children’s Research Institute. Baker also works in the lab of Dr. Sheela Sathyanarayana, a UW Medicine pediatrician.

A Drug That Needs Reevaluation?

“This medication was also approved decades ago, and may need reevaluation by the FDA,” said Sathyanarayana, the paper’s senior author. “Acetaminophen was never evaluated for fetal exposures in relation to long-term neurodevelopmental impacts.”

Acetaminophen is widely used during pregnancy, with 41-70% of pregnant individuals in the United States, Europe, and Asia reporting use. Despite acetaminophen’s classification as low risk by regulatory agencies such as the FDA, accumulating evidence suggests a potential link between prenatal acetaminophen exposure and adverse neurodevelopmental outcomes, including ADHD and ADHD autism spectrum disorder, the researchers noted.

Tracking Acetaminophen’s Impact Over a Decade

This research tracked a cohort of 307 women from 2006 to 2011, who agreed to give blood samples during their pregnancy. The researchers tracked plasma biomarkers for acetaminophen in the samples.

The children born to these mothers were followed for 8 to 10 years. Among the women who did not use acetaminophen during pregnancy, the rate of ADHD was 9%, but for the women who used acetaminophen, the ADHD rate among their offspring was 18%.

Acetaminophen metabolites were detected in 20.2% of maternal plasma samples. Children whose mothers had these biomarkers present in their plasma had a 3.15 times higher likelihood of an ADHD diagnosis compared with those without detected exposure.

Stronger Effects in Girls Than Boys

The association was stronger among daughters than sons, with the daughters of acetaminophen-exposed mothers showing a 6.16 times higher likelihood of ADHD while the association was weaker and nonsignificant in males. Researchers did not know why the association was stronger in females.

The investigators’ analysis used data from the Conditions Affecting Neurocognitive Development and Learning in Early Childhood (CANDLE) research cohort, which comprised 1,031 pregnant individuals in Memphis, Tenn., who were enrolled between 2006 and 2011.

By happenstance, and not by design, the study cohort included only Black women, Baker said, adding that the results could be generalized to women and children of any race or ethnicity.

A Commonly Recommended Drug

Mothers often are advised to turn to acetaminophen, the primary agent in Tylenol, rather than ibuprofen, which is more likely to adversely affect the fetal kidney or heart, Baker said.

“(Acetaminophen) is really the only option to control fever or pain during pregnancy,” he said.

So, what is a mother to do?

“There is obviously more work that needs to be done in this area,” he said. “And we need to continually update our guidance.”

Is There an Alternative?

For example, he suggested, during prenatal visits, patients should discuss the dosage of a drug that contains acetaminophen or talk about what pain it is intended to help manage, he said. Another drug class, such as triptans, is safe and effective for managing migraines, he added.

More work needs to be done to find out if some people can tolerate acetaminophen during pregnancy with no ill effects on the fetus while others cannot, he said.

He added that research findings on the effects of the drug and its potential risks during pregnancy have not been consistent.

Conflicting Studies Call for More Research

One study recently released in Sweden, showed no link between maternal acetaminophen use and ADHD in their children; while another study out of Norway, did in fact find a link. The study out of Sweden, however, relied on self-reported data, Baker noted.

“The study out of Sweden, however, reported that only 7% of pregnant individuals used acetaminophen,” Baker noted. “And that study could have underestimated the exposure.

“I think it goes back to how the data was collected,” he added. “The conflicting results mean that more research is needed.”

A Call for Updated Guidelines

Medical societies and the FDA should update guidance on the use of acetaminophen as safety data emerges, Sathyanarayana said.

Reference: “Associations of maternal blood biomarkers of prenatal APAP exposure with placental gene expression and child attention deficit hyperactivity disorder” by Brennan H. Baker, Theo K. Bammler, Emily S. Barrett, Nicole R. Bush, Brent R. Collett, Karen J. Derefinko, Daniel A. Enquobahrie, Catherine J. Karr, Kaja Z. LeWinn, Jiawang Liu, Christine T. Loftus, James W. MacDonald, Shanna H. Swan, Qi Zhao, Alison G. Paquette and Sheela Sathyanarayana, 6 February 2025, Nature Mental Health.
DOI: 10.1038/s44220-025-00387-6

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