Secretin is a peptide hormone that stimulates the secretion of digestive fluids from the pancreas, the production of pepsin from the stomach, and the production of bile from the liver. Autism is a chronic developmental disorder characterized by problems in social interaction, communication, and restrictive and repetitive interests and activities.
Interest in using secretin for treating autism was generated by two reports. One was about an autistic child who improved dramatically after receiving secretin during a study of pancreatic function. The other was an unblinded study of that child and two others . However, subsequent double-blind studies have found no evidence of effectiveness.
One study, published by Medscape’s online journal, involved 20 children who received either a intravenous secretin or placebo infusion at the beginning and the other substance at week 4. All subjects were extensively tested before treatment and at 4 and 8 weeks. No evidence was found that secretin administration influenced the test scores .
Another study, presented as an abstract in the Annals of Neurology, reported that results of with 44 patients, 25 of whom went through a four-week follow-up, were “unconvincing.” 
A third study, published in the New England Journal of Medicine, involved 28 autistic children and 28 normal children who were given a single intravenous dose of either synthetic secretin or a placebo and then evaluated with a symptom checklist. Both groups improved their scores, but there was no significant difference between the groups . An accompanying editorial cautioned:
The extensive media attention when substantive supporting data were absent was clearly premature and unfortunate. Parents scrambled to obtain this “cure” for their children in the absence of data on safety and efficacy—aided, in some cases, by well-meaning, if not well-informed, health care professionals. What makes an interesting television program may not, of course, be the same as what makes good science. . . .
Unfortunately, claims may be made on the basis of uncontrolled, single-case reports with all the attendant problems (e.g., ambiguities regarding diagnosis and the nature of the treatment and the fact that some children improve without intervention). Pursuing unproven treatments risks depleting the financial and psychosocial resources of families .
A two-part study involving 56 children with pervasive developmental disorders found that secretin injections “produced few clinically meaningful changes when compared to children given placebo injections.” 
Yet another study involving 95 children who received a single dose of either secretin or placebo found “no significant differences in language or autistic behaviour measures were observed at the 3-week follow-up between the groups.” 
In 2004, a review of 15 double-blind, randomized, controlled trials of secretin for autism concluded: “Almost none of the studies reported any significant effects and none concluded that secretin was effective.” 
Questions have also been raised about the safety of secretin injections. In a letter to the Wall Street Journal, seven professionals who had autistic children expressed concerns that (a) since injectable secretin is extracted from pig intestines, repeated doses might cause the body to make antibodies to secretin; (b) smaller protein fragments in secretin preparations might trigger immune reactions; (c) the amino acid cysteine, which is used to stabilize the preparations, could cause other adverse effects .
In 2012, the Cochrane Collaboration reviewed 16 studies of secretin that had been administered intravenously to a total of 900 children with autistic spectrum disorders (ASD). All of these studies were randomized and controlled and had used at least one standardized measure to evaluate outcome. The reviewer concluded:
There is no evidence that single or multiple dose intravenous secretin is effective and as such currently it should not be recommended or administered as a treatment for ASD. Further experimental assessment of secretin’s effectiveness for ASD can only be justified if there is new high-quality and replicated scientific evidence that either finds that secretin has a role in neurotransmission in a way that could benefit all children with ASD or identifies important subgroups of children with ASD who could benefit from secretin because of a proven link between the action of secretin and the known cause of their ASD, or the type of problems they are experiencing .
- Horvath K and others. Improved social and language skills after secretin administration in patients with autism spectrum disorders. Journal of the Association for Academic Minority Physicians 9:9-15, 1998.
- Owley T and others. A double-blind, placebo-controlled trial of secretin for the treatment of autistic disorder. Medscape General Medicine 1999.
- Chez MG, quoted in Bunk S. Secretin trials: A drug that might help, or hurt, autistic children is widely prescribed but is just now being tested. The Scientist 13(13):1, 1999.
- Sandler AD and others. Lack of benefit of a single dose of synthetic human secretin in the treatment of autism and pervasive developmental disorder. New England Journal of Medicine 341:1801-1806, 1999.
- Volkmar FR. Lessons from secretin. New England Journal of Medicine 341: 1999.
- Chez MG and others. Secretin and autism: A two-part clinical investigation. Journal of Autism and Developmental Disorders 30:87-94, 2000.
- Dunn-Geier J and others. Effect of secretin on children with autism: A randomized controlled trial. Developmental Medicine and Child Neurology 42:796-802, 2000.
- Sturmey P. Secretin is an ineffective treatment for pervasive developmental disabilities: a review of 15 double-blind randomized controlled trials. Research in Developmental Disabilities 26:87-97, 2005.
- Connors SL and others. Letter to the editor. Wall Street Journal, April 16, 1999.
- Williams K and others. Intravenous secretin for autism spectrum disorders (ASD). The Cochrane Collaboration, 2012.
This article was revised on May 11, 2015.