Cognitive behavioural therapy is an officially recommended treatment, but is available to less than 10% of patients in the UK with schizophrenia.

A study published in the Lancet indicates CBT could help the many who refuse antipsychotic medication. Experts say larger trials are needed.

About four-in-10 patients benefit from taking antipsychotic medication.

But the drugs do not work for the majority and they cause side-effects such as type 2 diabetes and weight gain.

Up to half of patients with schizophrenia end up not taking the drugs.

The study looked at cognitive behaviour therapy in 74 people.

The therapy works by identifying an individual patient’s problem – such as hearing voices, paranoid thinking or no longer going out of the house – and developing techniques to deal with them.

Prof Tony Morrison, director of the psychosis research unit at Greater Manchester West Mental Health Foundation Trust, said: “We found cognitive behavioural therapy did reduce symptoms and it also improved personal and social function and we demonstrated very comprehensively it is a safe and effective therapy.”

It worked in 46% of patients, approximately the same as for antipsychotics – although a head-to-head study directly comparing the two therapies has not been made.

Douglas Turkington, professor of psychiatry at Newcastle University, said: “One of our most interesting findings was that when given the option, most patients were agreeable to trying cognitive therapy.”

He added that drugs and cognitive therapy combined were the best treatment.

But while nearly everyone will be offered drugs, only a small proportion have access to cognitive behaviour therapy.

Prof Robin Murray, from the Institute of Psychiatry at King’s College London, said: “Many patients don’t like to take antipsychotics in the long term, this is not surprising as they have significant side-effects.

“So what to do for patients with continued psychotic symptoms who don’t want to take antipsychotics?

“Until now little was done except lecture them on how silly this was, with the usual result that the patients would simply stop attending.

“This study suggests that there may be a better option and that offering CBT is better than just leaving such patients to languish.”