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During a highly anticipated announcement today, President Donald Trump urged pregnant people to avoid taking Tylenol if possible because of the painkiller’s possible link to autism.

At the same time, Trump promoted leucovorin, a decades-old medication that mimics folic acid and is often used to restore nutrients in patients who are taking chemotherapy drugs. The folate-based treatment has been investigated in a few small clinical trials as a possible therapeutic for children with autism.

Before we get any further: The link between Tylenol and autism is unclear, and physician groups still recommend the medicine for pregnant people experiencing pain or fever, in consultation with their doctor. The link between vaccines and autism has been studied exhaustively, and no connection has been found.

Delivering leucovorin could, in theory, improve symptoms — and, in those small experiments, some parents and investigators have been thrilled with the results, as well as the strong safety profile.

But the evidence here is also still very limited; one study involved fewer than 50 patients. It is not clear whether this drug would work for all patients on the autism spectrum.

Trump and Health Secretary Robert F. Kennedy Jr. have been promising the American public answers on autism for months. But Monday’s announcement outpaces any science that could adequately back up the administration’s guidance. The National Institutes of Health has undertaken a massive review of autism science, but, according to the Washington Post, that research review was not completed in time for Trump’s White House announcement.’

Kennedy has long

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