Leucovorin as therapy for autism

What is it, what does it do, and does it work?

Amid the loud discussion of avoiding acetaminophen¹ during US President Donald J. Trump’s press conference regarding autism 22 September 2025, there was also notice that the US government had been reconsidering guidance about making another “drug” available to treat autism. That drug is actually a dietary supplement, (AKA folinic acid, folate, vitamin B9, and other names) that the US Food and Drug Administration refers to as “leucovorin.”²

What is leucovorin? What does it do? Does it help kids with autism?

What is it?

Leucovorin or “folinic acid,” which is chemically related to folic acid but not the same, is a form of B vitamin.³ It is composed two parts which are mirror images of each other (“enantiomeric?”) except that one (“levoleucovorin”) actually works in the body and the other (“dextroleucovorin?”) is pretty much excreted with urine (“Pub Chem” from the US National Library of Medicine).

Leucovorin is used by the body, as is vitamin B9, to facilitate production (and repair) of DNA. Without sufficient B9, the body doesn’t make and repair some proteins, especially those involved in red blood cell and (maybe) neural cell manufacture and restoration.

What are its uses?

Folinic acid has multiple uses. It may be employed to promote generation of red blood cells in people with anemia, for example. It can also be a part of legitimate therapy for folate deficiency during pregnancy, which can have deleterious effects on a developing fetus, causing neural tube defects such as spina bifida (Cleveland Clinic).