By Richard Hooper Face the Facts, BBC Radio 4
Children with autism are "falling prey to untested approaches" to the disorder, a leading charity has said.
The National Autistic Society said therapies with no supporting evidence were being sold to parents.
The warning comes after a BBC investigation found the use of dietary supplements and biomedical therapies being widely touted as a treatment.
There is no cure for autism and current best practice involves the use of behavioural and educational therapies.
BBC Radio 4's Face the Facts programme found that treatments, for which medicines regulator NICE says there is no clinical evidence, are readily available in the UK including:
- Hyperbaric oxygen chambers are being marketed with the claim that they can "counteract the underlying symptoms of autism"
- Biomedical doctors are prescribing children food supplements that cost £800 a month
- Chelation, a therapy developed to treat toxic metal poisoning, has been used by some parents to filter their child's blood
Commenting on the investigation, Carol Povey, the director of the National Autistic Society's Centre for Autism, said: "Too often, bold claims are made about therapies and interventions for people with autism without any supporting evidence.
"This is irresponsible and inappropriate, and we're concerned that some vulnerable families, desperate to find anything that might help, are falling prey to untested approaches."
One in 100 people have autism, and the cause of the disorder is thought to be genetic.
Francesca Happe, a professor of cognitive neuroscience at King's College London and one of the world's leading researchers into autism, said practitioners who "peddled" treatments without proof were "wicked".
She said the fact parents were prepared to pay for the treatments indicated that "we are not getting the message across that actually good intervention and education can achieve a huge amount for children with autism".
Face the Facts found hyperbaric oxygen chambers imported from the US and costing £25,000 were being purchased by parents for home use, despite NICE giving the therapy a "Do Not Use" recommendation because of doubts about its effectiveness and safety concerns.
The therapy involves breathing oxygen whilst sitting in a pressurised chamber.
Meanwhile, Deepa Korea, chief executive of Research Autism, told the programme that "there is not enough good quality research about what works and what doesn't" and called for greater funding into autism research.
A Department of Health representative said that "new joined-up arrangements" to be introduced this year will lead to children with autism having "better support".