FILE PHOTO: U.S. President Donald Trump, next to U.S. Secretary of Health and Human Services Robert F. Kennedy Jr., makes an announcement linking autism to childhood vaccines and to the use of popular pain medication Tylenol for pregnant women and children, claims which are not backed by decades of science, at the White House, in Washington, D.C., U.S., September 22, 2025. REUTERS/Kevin Lamarque/File Photo

By Ahmed Aboulenein

WASHINGTON (Reuters) -U.S. President Donald Trump on Friday repeated his call for pregnant women and young children to stop using popular pain medication Tylenol, defying widespread criticism from medical groups, and offered further healthcare advice not backed by science.

In an extraordinary news conference at the White House on Monday, Trump linked autism to childhood vaccines and the taking of Tylenol by women when pregnant, elevating claims not backed by scientific evidence to the forefront of U.S. health policy.

In a Truth Social post on Friday, the Republican president again called for the measles-mumps-rubella combination vaccine to be split into separate shots, and for children not to get the hepatitis B vaccine, normally given in the first 24 hours after birth, before the age of 12 years.

"Pregnant Women, DON’T USE TYLENOL UNLESS ABSOLUTELY NECESSARY, DON’T GIVE TYLENOL TO YOUR YOUNG CHILD FOR VIRTUALLY ANY REASON, BREAK UP THE MMR SHOT INTO THREE TOTALLY SEPARATE SHOTS (NOT MIXED!), TAKE CHICKEN P SHOT SEPARATELY, TAKE HEPATITAS B SHOT AT 12 YEARS OLD, OR OLDER, AND, IMPORTANTLY, TAKE VACCINE IN 5 SEPARATE MEDICAL VISITS!" Trump wrote.

The advice from Trump goes against that of medical societies, which cite data from numerous studies and decades of practice showing that acetaminophen, the active ingredient in Tylenol, is safe when used under a doctor's care while pregnant. Dozens of medical, research, and autism advocacy groups have decried the announcement.

Calling for several doctor visits is an unnecessary inconvenience that will likely lower vaccine uptake and prove an access barrier to many people, health experts have said.

The post on Friday and Monday's announcement are reminiscent of Trump's regular press briefings in the early months of the COVID-19 pandemic, when he would frequently dispense advice not founded on science, including his questioning of whether ingesting bleach would help and pushing treatments shown not to benefit COVID patients.

Though he did not mention autism on Friday, Trump's medical advice comes as his public health team sought this week to temper the initial message linking acetaminophen to autism.

The National Institutes of Health director in media appearances and the Food and Drug Administration commissioner in a written notice to physicians said there is an association, not a proven link, and that women should consult their doctors.

(Reporting by Ahmed Aboulenein; Additional reporting by Maiya Keidan and Brendan O'Brien; Editing by Bill Berkrot)