No evidence that Tylenol causes autism, say Health Canada, World Health Organization

TORONTO — Health Canada, the World Health Organization and Canadian autism experts say there is no evidence that taking Tylenol during pregnancy causes autism.

Health Canada and the WHO issued statements last night and this morning in response to U.S. President Donald Trump’s unproven claim linking the drug — whose generic name is acetaminophen — to the disorder.

Health Canada says acetaminophen is a “recommended treatment of pain or fever in pregnancy” and “has been used safely by millions of Canadians for decades, including during pregnancy and while breastfeeding.”

It says not treating fever and pain in pregnant women can pose risks to the unborn child.

Health Canada says people who are pregnant should take the medication at the lowest effective dose for the shortest time possible.

The agency says its advice is based on robust assessments of the available scientific evidence and that if any new evidence showed a risk, it would take action to update labels and inform health-care providers.

In its statement issued early Wednesday morning, the WHO said “extensive research has been undertaken over the past decade, including large-scale studies, looking into links between acetaminophen use during pregnancy and autism.”

“At this time, no consistent association has been established.”

Dr. Evdokia Anagnostou, co-leader of the Autism Research Centre at Holland Bloorview Kids Rehabilitation Hospital in Toronto, said acetaminophen is “the safest option we have for treating fever and pain during pregnancy” and is “backed by science.”

“To be clear, the evidence on autism being related to acetaminophen exposure during pregnancy is very weak. While early, smaller studies may have suggested there could be a connection, newer and large-scale studies have not found strong evidence to support this link,” Anagnostou said in a statement.

She said there is no one single cause of autism spectrum disorder and that researchers are studying “a complex interplay” of genetic and environmental factors.

“We already know that genes play a role in (at) least 15 to 25 per cent of autistic children and youth,” Anagnostou said.

The Society of Obstetricians and Gynaecologists of Canada issued a position statement on Sept. 12 in anticipation of the U.S. government’s comments on Tylenol and autism.

“The SOGC recommends the use of acetaminophen as a first-line therapeutic option for fever and pain in pregnancy when medically indicated at recommended doses for the shortest duration required,” the statement said.

“The benefits of acetaminophen for fever or pain in pregnancy are well recognized, as is the lack of safer alternatives in pregnancy. Untreated fever has been associated with miscarriage, fetal organ malformations, fetal cardiovascular complications, and even Autism Spectrum Disorder.”

Untreated pain can cause depression, anxiety and high blood pressure, the society said.

“Access to effective pain management is considered a human right, which women should not be denied just because they are pregnant.”

–With files from The Associated Press

This report by The Canadian Press was first published Sept. 24, 2025.

Canadian Press health coverage receives support through a partnership with the Canadian Medical Association. CP is solely responsible for this content.

Nicole Ireland, The Canadian Press