Tylenol and Autism

As early as 2008, researchers discovered a potential link between Tylenol and postnatal autism, and noted a rise in autism since 1980. During that period, the U.S. Centers for Disease Control and Prevention recommended substituting aspirin instead of acetaminophen for infants. Researchers initially thought the measles-mumps-rubella vaccinations caused autism. But research uncovered a significant association between acetaminophen and autism disorder in children ages 5 and younger.

Scientists also found an increased risk of ADHD and autism related to Tylenol use by those who are pregnant. However, some pregnant women who took Tylenol did not experience this issue. The correlation between Tylenol and ADHD and autism does not prove causation. So far, the research results aren’t definitive, and more studies are needed.

NIH Study Published in JAMA Psychiatry

Researchers from Johns Hopkins University conducted a study in 2019 funded by the National Institutes of Health. The results suggest that mothers who use acetaminophen during pregnancy have a higher risk of having a child with ADHD and autism spectrum disorder. They used data from the Boston Birth Cohort study, which measured the amount of acetaminophen in umbilical cord blood from a sample of 996 births. When children reached an average age of 8.9 years old, 6.6% had ASD only, 25.8% had ADHD only and 4.2% had ASD and ADHD.

Researchers also found a correlation between the risk level and the quantity of acetaminophen each mother consumed. They divided the subjects into thirds based on the level of exposure to acetaminophen (low, medium and high). The risk of having a child with ADHD and ASD was more than two times higher in the middle and higher thirds than in the lower third. Based on those findings, they concluded there was a link between acetaminophen exposure and ADHD and ASD, and said data from future studies might help solidify their conclusions.

WP Lab, Duke University and Chapel Hill Study

This combination study documented that there wasn’t enough information to support the 1970s belief that using acetaminophen during pregnancy and early childhood was safe. People assumed that children and unborn babies had the same effects from acetaminophen as adults. Therefore, they didn’t think it would impact neurodevelopment.

Today, at least 14 epidemiological studies show that use of acetaminophen, also known as paracetamol, in pregnancy can lead to neurodevelopmental problems. According to these studies, prenatal exposure to paracetamol increases the risk of neurodevelopmental delays, ADHD and ASD.

European Research Council-Funded

This 2021 meta-analysis involved more than 70,000 mother-child pairs from European birth cohorts. Researchers used interviews and questions to assess mothers with prenatal and postnatal acetaminophen exposure of up to 18 months. Then, they observed the children for four to 12 years for symptoms of autism spectrum disorder and ADHD.

Children with prenatal exposure to acetaminophen were 21% more likely to have ADHD with clinical symptoms than nonexposed children, according to this study. The likelihood of autistic spectrum conditions was 19% higher.

Volumes of research show the potential dangers of pregnant women taking Tylenol. Even though the drug can help ease fevers, back pain and headaches during pregnancy, it’s essential that women — and their doctors — weigh the risks before it is used. According to these studies, the more paracetamol you take during pregnancy, the higher the risk of delivering a child with ADHD and autism.

Besides neurodevelopmental issues, other Tylenol side effects can affect pregnant women and their babies. Humans process acetaminophen through the liver, and high doses or prolonged use of Tylenol can damage the liver. Pregnant women with preexisting liver conditions or who are taking other medications that can affect liver function should exercise caution when adding Tylenol to the mix.

Some studies suggest that exposure to Tylenol in the womb may also affect a baby’s reproductive system and increase the risk of infertility later in life. Women who intend to get pregnant should be cautious about using paracetamol during pregnancy.

Other increased risks of a child being born with autism include a family history of autism, the child’s sex, a woman’s age and extremely premature births. Boys are about four times more likely to develop autism spectrum disorder than girls. The older the mother is during conception, the greater the risk for autism.

In the past few years, some women delivered babies with autism and ADHD after using Tylenol while pregnant. They later filed lawsuits against Tylenol manufacturers, claiming the drug caused autism in their children. To support their Tylenol lawsuits, plaintiffs relied on a study suggesting a potential link between Tylenol use during pregnancy and an increased risk of autism in children.

But this study was inconclusive, and some studies have not found a link between Tylenol and ADHD or autism. The makers of Tylenol maintain their product is safe when used as directed. They say they have seen no evidence to suggest a link between Tylenol and autism.

The drugmakers’ stance hasn’t stopped parents of some children with autism from pursuing legal action. These legal claims typically seek compensation for medical expenses and damages for the emotional pain and suffering caused by their children’s diagnosis. As the legal battle between Tylenol manufacturers and affected parents continues, scientists have yet to establish a clear link between prenatal autism and Tylenol. Nonetheless, research shows a close association between the two.