Acetaminophen is a common pain and fever reliever medication used for many ailments, including headaches, muscle aches, minor arthritis, menstrual cramps, toothaches, backaches, colds and flu, and fever. It is a common ingredient in more than 600 medicines like Tylenol, with the recommended daily intake limit being 4,000 milligrams (4 grams) over 24 hours, and it is also recommended to avoid taking it with alcohol.
The purpose of this piece is to briefly discuss acetaminophen use and its history, as it recently came under fire from President Trump, who directly stated that using acetaminophen during pregnancy causes autism in newborns. President Trump cited numerous studies that face scrutiny within the scientific community with regards to their legitimacy in directly connecting acetaminophen to autism, but he remained adamant that his administration would solve this problem.
Labroots recently discussed an August 2024 study published in Environmental Health examining the impacts of using acetaminophen during pregnancy, specifically regarding an increased risk of newborns born with neurodevelopmental disorders (NDDs) like autism spectrum disorder (ASD) and attention-deficit/hyperactivity disorder (ADHD). In the end, the study found “evidence consistent with an association between acetaminophen exposure during pregnancy and increased incidence of NDDs.”
Studies as recently as 2019 and 2021 discussed associated links between acetaminophen, ADHD, and ASD, with each study conducting interviews and questionnaires with 996 and 73,881 mother-infant pairs, respectively. Each study explored different aspects of acetaminophen exposure, with the 2019 study exploring cord plasma biomarkers while the 2021 study focused on overall acetaminophen exposure during pregnancy.
In the end, both studies had similar conclusions, with the 2019 study noting, “Cord biomarkers of fetal exposure to acetaminophen were associated with significantly increased risk of childhood ADHD and ASD in a dose-response fashion.” Additionally, the 2021 study noted, “Boys and girls showed higher odds for ASC and ADHD symptoms after prenatal exposure, though these associations were slightly stronger among boys.”
However, the American College of Obstetricians and Gynecologists (ACOG) quickly refuted any claims regarding a connection between using acetaminophen during pregnancy and NDDs. They emphasized that the clinical practice of using acetaminophen during pregnancy will continue unabated.
The ACOG statement noted that, “the current weight of evidence does not support a causal link between prenatal acetaminophen use and neurodevelopmental disorders. At this time, no change in clinical practice is warranted based on new publications and ACOG’s recommendations for the use of acetaminophen for specific indications remain current.”
Potential reasons for the competing results claiming that acetaminophen causes ASD and/or ADHD include exposure measurement and outcome definition. For exposure measurement, studies involving cord biomarkers, such as the 2019 study, have data that is more accurate regarding prenatal exposure; however, they have small sample sizes. In contrast, studies that involve interviews, such as the 2021 study, have large sample sizes but rely on maternal recall instead of biological data.
Acetaminophen was first synthesized in 1877 by the American chemist, Harmon Morthrup Morse, although it took almost 100 years until its medical potential was achieved. During this time, phenacetin controlled the market despite harsh side effects like kidney toxicity and blood effects, which were exposed during the 1940s, and acetaminophen was designated as a safe alternative.
Acetaminophen became commercially available in the 1950s and became mainstream throughout the 1960s and 1970s. Despite a series of events, including a tampering crisis in 1982 and upgraded formulas in the 2010s, acetaminophen has remained one of the most widely recommended and used pain/fever relievers worldwide.
One of the first instances of linking acetaminophen with autism was made by American chemist, Dr. William Shaw, who proposed in 1993 that there was a connection between acetaminophen and autism, along with causing yeast infections and additional health complications. During the interview, Dr. Shaw claimed to be the foremost expert on autism worldwide while claiming that acetaminophen caused it.
“Another autism factor led me to pinpoint acetaminophen,” Dr. Shaw said in the interview. “You may not be aware, but there’s virtually no autism in Cuba. They completely ban the use of acetaminophen except by prescription. There’s no over the counter acetaminophen in that country and so they have something like a hundred times less autism than the U.S.”
While President Trump has also pushed the rhetoric that Cuba doesn’t have autism cases due to the lack of acetaminophen, a September 2025 article stated that autism does exist in Cuba, with Cuban doctors improving diagnostic measures and public awareness.
As the discourse around the connection between acetaminophen and autism continues to rage, experts emphasize that the use of acetaminophen continues to be safe, and individuals should consult with their doctor with any concerns they might have before using acetaminophen.
Sources: ScienceNews, Labroots, JAMA Psychiatry, European Journal of Epidemiology, American College of Obstetricians and Gynecologists, Wikipedia, Wikipedia (1), International Medicine: A Clinician’s Journal, The Latin Times