Kenvue Stock Tumbles on Report Kennedy Will Link Autism and Tylenol

Tylenol accounts for more than 15% of Kenvue U.S. retail sales, according to one Wall Street estimate. (Gabby Jones/Bloomberg)

Kenvue shares were down as much as 16% in midday trading Friday following a Wall Street Journal report that U.S. health secretary Robert F. Kennedy Jr. plans to issue a report linking the use of pain reliever Tylenol by pregnant women to autism cases.

Acetaminophen, the active ingredient in Tylenol, is one of the few pain relief and fever reduction medicines recommended for pregnant women. A number of studies have pointed to possible links between acetaminophen taken during pregnancy and autism, though doctors continue to recommend the medicine, and more recent research has cast significant doubt on any linkage.

Kenvue, which spun out of Johnson & Johnson in 2023, has faced hundreds of lawsuits claiming that prenatal exposure to Tylenol was associated with neurological disorders in children. Those cases have struggled in the courts, and in August of 2024, a federal judge granted summary judgement in favor of Kenvue and other defendants, dismissing all the cases brought in federal court.

“We have continuously evaluated the science and continue to believe there is no causal link between acetaminophen use during pregnancy and autism,” Kenvue said in a statement.

In a statement to Barron’s, HHS press secretary Emily Hilliard said that claims about the contents of its forthcoming autism report “are nothing more than speculation.” Hilliard said that the agency is “using gold-standard science to get to the bottom of America’s unprecedented rise in autism rates.”

While Kenvue doesn’t break out Tylenol sales, analysts say that the pain reliever is one of the company’s largest two brands, alongside skin care brand Neutrogena. Jefferies analysts wrote in June that Tylenol and Neutrogena each account for more than 15% of the company’s U.S. retail sales.

In a note Friday afternoon, BNP Paribas analyst Navann Ty called the Kenvue selloff overdone. “In our view, the hurdle to proving causation is high, particularly given that the litigation previously concluded in Kenvue’s favor,” Ty wrote.

Though some studies have suggested a possible link between prenatal exposure to acetaminophen and a higher risk of autism and ADHD, more recent research has suggested that earlier studies were flawed, and U.S. medical organizations say that acetaminophen use is appropriate during pregnancy.

While scientists have argued over uncertain evidence of a link between acetaminophen and autism, uncontrolled fever in pregnant women can increase the risk of miscarriage or preterm labor. Acetaminophen is one of the few available options for controlling pain and fever during pregnancy, and medical organizations have not advised against taking the medicine.

“Patients should not be frightened away from the many benefits of acetaminophen,” the American College of Obstetricians and Gynecologists said in 2021 statement.

Debate over a possible risk tied to pregnant women taking acetaminophen has existed at least since 2019, when a 10-year study funded by the National Institutes of Health found that mother-infant pairs whose cord plasma showed evidence of acetaminophen exposure had a “significantly increased” risk of ADHD and autism spectrum disorder in childhood.

More recent research has pushed back on those concerns. A paper published in the Journal of the American Medical Association that reviewed the medical records of all of the children born in Sweden from 1995 to 2019 found no association between acetaminophen use during pregnancy and the risk of autism, ADHD, or intellectual disability. The authors wrote that their findings imply that earlier studies were wrong. “This suggests that associations observed in other models may have been attributable to confounding,” they wrote.

Write to Josh Nathan-Kazis at josh.nathan-kazis@barrons.com