Tylenol and Autism - The Data

Today the Trump regime and RFKjr have linked rising cases of autism to the popular painkiller, acetaminophen (aka: Tylenol). Acetaminophen (APAP) has been the "go-to" safe option to treat pain or fever in pregnant women for decades. The possible link between autism and acetaminophen has been looked at and reported in thousands of studies in the science literature and the overwhelming majority has FOUND NO CAUSAL LINK BETWEEN AUTISM AND EXPOSURE TO ACETAMINOPHEN IN THE WOMB.

Trump said the FDA will issue a physician's notice about the risk of patients using acetaminophen during pregnancy and will launch a nationwide campaign to inform patients about the risk. "Taking Tylenol is not good", he says and he encourages women with fever to "tough it out".

In the USA up to 65% of pregnant women have used APAP and worldwide more than 50% of pregnant women use it for pain and fever. Severe pain and fever, left untreated, could potentially affect the developing fetus or the mother and fever is a well-accepted risk factor for multiple disorders including neural tube defects and later cardiovascular disorders.

There have been large population studies that looked at siblings, which account for shared genetic and environmental effects that found no relationship between APAP and autism. (Note that 74-85% of autism risk is considered genetic with common variants of genes ). A Swedish national cohort study (2024) looked at 1.5 million children and found a small increased risk of autism (0.09% increased risk) for autism at 10 years of age between APAP exposed and unexposed children was that was nullified when they controlled for familial confounding. This means it's important to interpret results as being "caused by" versus being "associated with". There was no causation found in these 1.5 million children. A large Japanese nationwide birth study (2025) also found no cause.

Studies on rats and mice models have found effects of APAP on fetus development. It's very hard to extrapolate mouse data to humans due to size (not to mention genetics) but human studies have shown doses to 1,430mg/kg a day to be safe. Tylenol usually comes in 325 or 500mg tablets.

Despite what you hear from MAHA and Trump...science is complex, difficult and rigorous. It requires expertise to conduct and interpret studies. For example, several biological pathways are involved in neurodevelopment and the risk of autism spectrum disorder:

• Oxidative stress and mitochondrial dysfunction

• Endocrine disruption

• Prostaglandin and cannabinoid signaling

• Gene expression

• Human biomarkers

• Environmental

• Birth complications

• Advanced parental age and births under 12 months apart

There may be political reasons for this strange warning to come from the President.

1. RFKjr. stated publicly that he would "identify and eliminate" the cause of autism by September. Scientists were obviously questioning such a weird statement.

2. President Trump may be deflecting from the pressure to release the Epstein Files by making more "News" and controversy. "I think you're going to find it to be amazing", Trump told a memorial rally for Charlie Kirk on Sept 21. "I think we found an answer to autism".

3. Maybe people in power are "shorting" Tylenol stock to make a profit. Kenvue Corp. (a spin off of Johnson and Johnson) stock dropped by 7.4% today.

4. The FDA fired thousands of scientists in early 2025, leading to a significant loss of expertise within the agency.

5. The slashing of staff and silencing of career scientists at the CDC has put the health of Americans at dangerous risk.

It's really a shame that we cannot trust the government to give accurate information about public health.

I trust The American College of Obstetricians and Gynecologists, The Society for Maternal and Fetal Medicine, The American Academy of Pediatrics, The American Academy of Physicians, The Academy of Family Physicians and the thousands of doctors and scientist around the world who have the best interest of humans in mind.