US President Donald Trump on Monday talked about some unproven claims linking Tylenol, vaccines, and autism, without giving any new medical evidence. During a long and confusing White House press briefing, Trump instructed the pregnant women several times not to take Tylenol, which is also called acetaminophen. He also advised mothers not to give the medicine to their babies.

“Don’t take tylenol,” Trump repeated old and widely disproven claims that vaccine ingredients or giving multiple shots close together could be linked to rising autism cases in the US. However, he did not provide any proof. It is worth noting here that healthcare professionals and doctors have long considered acetaminophen one of the safest painkillers for pregnant women, saying that untreated pain or fever can be harmful for both the mother and the baby.

Trump’s announcement seemed to be based on existing studies rather than new research. It comes as the “Make America Healthy Again” movement continues to demand answers about what causes autism.

‘Don’t Take Tylenol’: Trump revives debate on autism treatment without proof

“Taking Tylenol is not good,” Trump said, adding, “For this reason, they are strongly recommending that women limit Tylenol use during pregnancy unless medically necessary. That’s for instance, in cases of extremely high fever that you feel you can’t tough it out.”

During the event, Trump also noted that the Food and Drug Administration would start telling doctors that acetaminophen “can be associated” with a higher risk of autism. He did not provide any immediate evidence or justification to prove his new claims.

The announcement also highlighted Trump’s ongoing interest in autism and his doubts about the infants’ vaccination schedule.

Trump’s claims on infant vaccination schedule

Trump suggested big changes at the event on how babies should be vaccinated. He claimed, again without giving any proof, that newborns do not need the Hepatitis B vaccine, which protects against a serious and highly contagious disease. Echoing anti-vaccine views, Trump said, “I would say, wait until the baby is 12 years old and formed.”

Is Tylenol really linked to autism? Here’s what medical experts and research say

Studies on the link between autism and acetaminophen have shown mixed results, according to Bloomberg. Most research so far has been observational, meaning scientists look at data from a group of people and try to see if there’s a connection. Because many other factors can influence the outcome, these studies can’t prove cause and effect. Their findings are also often hard to repeat.

Medical experts warned that Trump’s claim goes against decades of proof showing that giving newborns the Hepatitis B vaccine within 24 hours of birth is vital to stop mothers from passing the disease to their babies. Hepatitis B can damage the liver and even cause cancer.

The announcement has come after a recent meeting of a special advisory group set up by Health Secretary Robert F. Kennedy Jr. The group chose not to support delaying the first Hepatitis B shot by a month. Their decision to keep discussing the issue gave public health experts some relief, as many fear that postponing the vaccine could be dangerous.

On the subject of tylenol, health experts have called Trump’s comments irresponsible. New York University bioethicist Art Caplan told Associated Press that it was “the saddest display of a lack of evidence, rumors, recycling old myths, lousy advice, outright lies, and dangerous advice I have ever witnessed by anyone in authority.”

David Mandell, an autism expert at the University of Pennsylvania told AP that some studies have suggested a possible connection between the two when taken during pregnancy, but many others do not support this claim. All in all, research on whether Tylenol is linked to autism is still unclear.

US regulator approves drug for autism treatment

Meanwhile, the FDA on Monday said that it has taken initial steps to approve leucovorin, a folic acid metabolite, as a possible treatment for some people with autism. The idea is based on a theory that some people may not have enough folate, a type of vitamin B, in the brain, and giving them more might ease certain symptoms, reported AP.

Women are already advised to take folic acid before pregnancy and during pregnancy to lower the risk of birth defects. Experts say this may also possibly reduce the risk of autism, the report added.

Leucovorin is already sold for other medical conditions and is used by some families hoping it will help with autism. But experts like Tager-Flusberg warned that only a few small, early studies have been done so far. “Is this something worth pursuing? Yes, it is in potentially a subset of individuals,” she told AP, but added that there needs to be a wider and thorough study to really prove if this really works.

Autism is not a disease but a developmental condition that shows up differently in each person. It affects about 1 in 31 children in the US, according to the CDC. This is a big increase compared to a few years ago. Scientists have said there is no single cause of autism and research shows that both genetic and environmental factors may play a role, reported AP. Experts warn that claims suggesting otherwise ignore decades of scientific evidence.

Disclaimer: Always consults a doctor before starting any diet or fitness routine. Always seek the advice of your doctor with any questions about a medical condition.