Leukovorin is a drug originally intended to treat cerebral folate deficiency and to alleviate the side effects of chemotherapy[1]. Some doctors have begun to prescribe it outside the approved guidelines (as an "off-label" drug) for the treatment of autism, although there is a lack of substantial scientific evidence that cerebral folate deficiency plays a role in the development of autism[1]. There are individual cases, such as the boy Mason, who reportedly showed improvement in symptoms after starting leucovorin[1]. However, doctors warn that claims of leucovorin's effectiveness in autism are ahead of scientific knowledge and there is a lack of evidence supporting its routine use for this purpose[1]. Another problem is that leucovorin is a cheap drug and pharmaceutical companies do not see commercial potential in it, which complicates its official approval for the treatment of autistic symptoms[1]. Experts stress the need for more research before this drug can be used more widely for autism[1].