Does Tylenol Cause Autism? A Review of the Science Linking Tylenol and Autism Spectrum Disorder

The same research that has been the basis of Tylenol autism lawsuits being pursued by families nationwide, is now being cited by federal health officials to justify new pregnancy warnings for acetaminophen drugs.

Over the past few months, there has been renewed attention on the risks associated with use of acetaminophen during pregnancy, following recent warnings issued by federal health officials. However, this comes after years of different studies being published in peer-reviewed medical journals, which have been cited by families pursuing Tylenol autism lawsuits for years.

A renewed wave of attention has returned to the Tylenol autism litigation following a major announcement by federal health officials in late 2025, which could breathe new life into lawsuits that were previously dismissed by the courts.

In September 2025, the U.S. Food and Drug Administration (FDA) and Department of Health and Human Services (HHS) announced that new pregnancy warnings will be added to Tylenol and other acetaminophen-containing medications, advising doctors and pregnant women to limit use due to potential risks of developmental disorders, including autism and ADHD.

Tylenol has been one of the most commonly recommended pain relievers during pregnancy for decades, based on the widespread belief that it was the safest option, compared to aspirin or ibuprofen. However, that perception began to shift after a series of peer-reviewed studies found that frequent prenatal exposure to acetaminophen was associated with significantly higher rates of autism spectrum disorder (ASD) and attention deficit hyperactivity disorder (ADHD) in children.

As public awareness grew, families across the United States began filing lawsuits against Johnson & Johnson and other manufacturers of generic acetaminophen products, each raising similar allegations  that drug makers were ignoring years of research, by failing to warn about the risks of neurological disorders in children.

Tylenol Autism Lawsuits Stalled

In response to a growing number of complaints being filed throughout the federal court system, the U.S. Judicial Panel on Multidistrict Litigation (JPML) centralized all federal Tylenol autism lawsuits before Judge Denise Cote in the Southern District of New York in October 2022, forming MDL No. 3043 to coordinate discovery and expert challenges.

However, in December 2023, Judge Cote issued a sweeping order excluding all of the plaintiffs’ expert witnesses under the federal Daubert standard, determining that the scientific methods used to link acetaminophen to autism were not reliable enough to present to a jury. As a result, the entire MDL was dismissed before any bellwether trials could take place.

That decision is now under active appeal before the Second Circuit Court of Appeals, and the landscape has shifted dramatically. Plaintiffs argue that the FDA’s new national warning requirement and HHS’s decision to fund autism risk research directly validate the very scientific concerns that drug makers previously argued were speculative.

If the appeals court rules that Judge Cote erred in excluding the expert testimony, particularly in light of this regulatory shift, the Tylenol litigation could reopen and proceed to trial, signaling a major turning point for thousands of families.

In this featured post, AboutLawsuits.com will examine the research linking prenatal acetaminophen use to autism spectrum disorder, the same scientific evidence now referenced by federal health officials in support of new pregnancy warnings, and how that could reopen the door for Tylenol autism lawsuits.

Is Tylenol Safe To Take During Pregnancy?

Moderate use of Tylenol during pregnancy has been considered safe for decades, and most doctors continue to indicate pregnant women can take the pain medication on occasion.

However, lawsuits point to a number of studies that have warned the risk of unborn children developing autism spectrum disorder may vary greatly, depending on the amount of acetaminophen used, and what trimester of the pregnancy the pain medication is taken.

How much Tylenol is safe to take while pregnant?

Johnson & Johnson and other drug makers have not provided adequate information about the amount of Tylenol that is safe for pregnant women to take, according to lawsuits.

As a result, most pregnant women follow the standard warnings not to exceed the maximum recommended dose of 4,000 milligrams of acetaminophen daily, since there are no specific warnings about the potential autism risk when Tylenol is regularly and routinely taken while pregnant.

Many of the mothers of children diagnosed with autism after use of Tylenol during pregnancy report that they routinely used the pain medication 3 to 6 times per week, often throughout the entire course of their pregnancy, according to complaints filed.

Families pursuing Tylenol lawsuits now indicate that they never would have taken the pain medication as frequently if they had been aware of information available to the drug makers about the potential autism risk, and indicate that the Tylenol warning label should have made it clear that pregnant women should use the lowest effective dose for the shortest possible frequency to treat pain or fever.

How Can Tylenol Cause Autism?

Independent research and scientific studies have identified several mechanisms of action that appear to explain how Tylenol may cause autism when used during pregnancy.

While many families initially believe that autism was caused by genetic factors, there is evidence that acetaminophen can impact the brain of a developing fetus, resulting in a number of side effects that may cause autism, including:

• Hormonal Disruption: Acetaminophen has been shown to influence hormone levels, such as reducing testosterone production, which may play a role in brain development and the risk of neurodevelopmental disorders like autism.
• Oxidative Stress: Acetaminophen is metabolized in the liver, leading to the production of reactive oxygen species (ROS) and oxidative stress. Excessive oxidative stress during critical periods of fetal brain development could potentially disrupt normal neural development and cause children to develop autism and other developmental disorders.
• Glutathione Depletion: Acetaminophen has been shown to deplete levels of glutathione, a key antioxidant in the body. Glutathione plays a crucial role in protecting cells, including neurons, from oxidative damage. Reduced glutathione levels may lead to increased vulnerability to oxidative stress and potential neurodevelopmental disorders, such as autism or ADHD.
• Immune System Modulation: Acetaminophen may influence immune responses, including inflammation and immune system regulation. Alterations in immune function during pregnancy could potentially impact child development and put unborn children at higher risk of developing neurodevelopmental disorders.

Studies: Acetaminophen Exposure Linked to Autism Spectrum Disorder

Researchers have examined the association between Tylenol use during pregnancy and the risk of autism through observational studies and epidemiological research, since it would be unethical and illegal to conduct studies in which pregnant women are given acetaminophen to investigate whether it causes autism.

Many of the findings published in recent years have identified strong links between acetaminophen use during pregnancy and increased risks of autism or ADHD diagnosis in children, providing strong evidence of a potential association. Here are some key findings from the studies:

Scientists Call For Tylenol Pregnancy Autism Risk Warning Labels

Serious concerns surrounding acetaminophen use during pregnancy were raised by 91 scientists and public health professionals in a Consensus Statement published in Nature Reviews Endocrinology in September 2021.

The group of scientists formed their Consensus Statement after reviewing 29 studies on acetaminophen exposure and adverse neurodevelopmental outcomes, which involved more than 220,000 mother-child pairs across the globe.

Of the studies, 26 indicated that prenatal exposure to acetaminophen, as well as perinatal use or exposure, negatively impacts fetal brain development, increasing a child’s risk of autism or ADHD diagnosis.

Scientists specifically stated the most detrimental effects of long-term use and exposure to acetaminophen for children were found at the beginning of the third trimester and around the time of birth.

Given the mounting human scientific evidence supporting Tylenol’s link to autism, the authors urged the FDA and EMA, as well as obstetric and gynecological societies, to review all available data and provide an evidence-based evaluation of risk to inform pregnant women and their healthcare professionals.

The statement further recommended warning labels should be included on acetaminophen packaging while additional research and risk-evaluations are performed. However, manufacturers chose not to take this action for years, until the recent requirement by federal health officials.

Children Exposed to Acetaminophen During Pregnancy Linked To Higher Rates of Autism Spectrum Disorder

In a study published in the European Journal of Epidemiology in May 2021, researchers analyzed data from 73,881 children, and found a clear link between prenatal acetaminophen exposure and an increased risk for autism and ADHD diagnoses.

Results showed that children prenatally exposed to acetaminophen are 19% more likely to have Autism symptoms when compared to children who were not exposed to acetaminophen during pregnancy.

To further reinforce the risk of infant exposure to acetaminophen during pregnancy, the study did not find any association between postnatal exposure to acetaminophen and autism.

Pregnant Women With Acetaminophen In Cord Blood Samples Birthed Children With Higher Autism

In a study published in JAMA Psychiatry in October 2019, researchers looked at 996 mother-infant pairs to determine whether the amount of acetaminophen found in umbilical cord blood samples increased the rate of both autism spectrum disorder and attention deficit hyperactivity disorder.

Researchers found the chances of an autism spectrum disorder diagnosis increased significantly when higher levels of acetaminophen were found in umbilical cord blood samples.

Specifically, the children with the highest level of acetaminophen in umbilical cord blood samples were at a 262% increased risk of Autism spectrum disorder diagnosis when compared to the lowest level.

Single Use of Acetaminophen During Pregnancy Increased Autism Risks By 41%

According to a study published in the International Journal of Epidemiology in 2016, authors highlighted the risk factors of taking acetaminophen during pregnancy. Researchers found that among 2,644 mother-child pairs recruited during pregnancy, even a single use of Tylenol during pregnancy increased the risk of autism by 41%.

Researchers further found that frequent use of acetaminophen pain relief drugs more than doubled the risk of hyperactivity and impulse disorders. Additionally, researchers indicated the frequent use of acetaminophen negatively impacted fetal development and increased the overall chances of a child developing a complex developmental disorder, stating;

“Prenatal acetaminophen exposure was associated with a greater number of autism spectrum symptoms in males and showed adverse effects on attention-related outcomes for both genders. These associations seem to be dependent on the frequency of exposure.”
-Journal of Epidemiology: 2016

Acetaminophen Use During Early Pregnancy Increases Child’s Risk Of Autism Spectrum Disorder Symptoms

A study was published in the International Society of for Autism Research in 2015, finding that prenatal use of acetaminophen was associated with an increased risk of autism spectrum disorder, accompanied by hyperactivity symptoms

Researchers collected data from the Danish National Birth Cohort study, which followed 64,322 children and mothers for an average of 12.7 years. According to the findings, researchers identified prenatal use of acetaminophen increased the risk of autism spectrum disorder with hyperactivity symptoms by 51%. The risk was higher with prolonged use of 20 or more weeks.

The findings of this study suggest that acetaminophen exposure early in fetal life may specifically impact hyperactive behavioral phenotypes. The authors concluded that in-utero exposure to acetaminophen could lead to neurodevelopmental injuries, including ASD, and urged pregnant women to consider alternatives for managing pain and fever.

Fetal Exposure To Acetaminophen Impacts Brain Development In Mice

Since human trials are illegal, researchers have explored the use of acetaminophen in mice to determine whether the pain relievers exposure to mice in utero caused newborn mice to develop autism.

In a study published in the journal Frontiers in Toxicology, researchers evaluated the impact of neonatal exposure to relevant doses of Tylenol on mice behavior. The behaviors of the exposed mice were evaluated in the days following birth.

The results found that mice neonatally exposed to acetaminophen showed altered and spontaneous behavior, reduced memory, and both learning and cognitive challenges compared to mice born without exposure to acetaminophen.

In the study on mice, researchers further sought to understand how acetaminophen altered the developing brain. The study indicated that after neonatal mice were exposed to acetaminophen, an increase in markers for oxidative stress were identified in the part of the brain that are responsible for emotion, memory, and the autonomic nervous system.

The authors stated that even at low doses, such persistent and negative effects on a developing brain could induce the risk for brain damage.

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Regulators Side With Evidence Supporting Tylenol-Autism Link in 2025

In a landmark move, the FDA released a Notice to Physicians and a formal press announcement on September 22, 2025, acknowledging that evidence has accumulated suggesting that the use of acetaminophen by pregnant women may be associated with an increased risk of neurological conditions such as autism and ADHD in children.

The agency simultaneously initiated the process to update acetaminophen labels nationwide to reflect that potential risk. U.S. Food and Drug Administration

FDA Commissioner Martin Makary emphasized that the decision was made “to make parents and doctors aware of a considerable body of evidence about potential risks associated with acetaminophen,” while still maintaining that causation has not been definitively established. The agency further noted:

“Evidence in recent years has suggested a correlation between acetaminophen use during pregnancy and subsequent diagnosis of conditions like autism and ADHD. Multiple large-scale cohort studies, including the Nurses’ Health Study II and the Boston Birth Cohort, find this association.”
-U.S. Food and Drug Administration: September 2025

What Happens Next in the Tylenol Autism Litigation?

With the appeal pending and federal regulators now instructing physicians to limit acetaminophen use during pregnancy, plaintiffs argue that the earlier dismissal should be reconsidered. 

The Second Circuit Court of Appeals is expected to determine whether the MDL should be reinstated, which would reopen discovery and allow new expert testimony based on evolving federal policy and current science.

If the appellate court rules in favor of plaintiffs, Judge Denise Cote could be directed to resume proceedings, potentially scheduling a new bellwether trial process, where representative cases are prepared for early jury evaluation.

Could New Federal Warnings Lead to Tylenol Autism Settlements?

The FDA and HHS label action marks a significant shift in government stance, and may increase pressure on drug makers to reassess their litigation strategy. Tylenol lawyers indicate that if expert evidence is allowed back into the case, defendants may prefer to negotiate early resolutions rather than face jury trials involving new federally backed risk language.

Even without a full reinstatement of the MDL, Tylenol autism lawsuits continue to be pursued in various different state courts, particularly in jurisdictions that use a different standard for expert testimony than the federal Daubert rule.

Have a Tylenol Lawyer Review Your Child’s Autism Case

It is important to speak with an attorney experienced in Tylenol autism and ADHD claims to preserve your family’s legal rights, especially as federal regulators reevaluate the risks and the litigation shows signs of reopening. A lawyer can review your child’s diagnosis, document prenatal acetaminophen exposure, and advise whether your family may be eligible to pursue compensation.

Tylenol autism law firms are accepting cases on a contingency basis, meaning there are no fees unless a recovery is obtained, and free case evaluations are available to help families understand their options as the litigation develops.your case.