Bespoke web or phone-based psychological therapy should be offered to people with severe irritable bowel syndrome (IBS), researchers say.
Their work, published in the journal Gut, shows cognitive behavioural therapy (CBT) could reduce symptoms – even when not delivered face-to-face.
England's health watchdog already recommends face-to-face CBT for people who have IBS, despite other treatment.
But researchers say many people are unable to access it.
Irritable bowel syndrome is a common and often life-long condition that affects the bowels – it can cause stomach cramps, bloating, diarrhoea and constipation.
There's no cure, but changes to diet and medicines can help control the symptoms.
The team of scientists from the University of Southampton and King's College London, say their newly designed phone and web-based CBT requires fewer therapist hours and could be offered more widely to people who need it.
"I don't have symptoms anymore."
Laura Day, 31, a freelance journalist living in London, told the BBC that taking part in the web-based therapy was "the best thing she had ever done".
She remembers being "the kid with the nervous tummy" from the age of about five, and finding mornings particularly difficult.
She said she would often spend a long time on the loo, opening her bowels two or three times before she left the house and everything had to revolve around her IBS.
She used to plan emergency toilet stops on her way to work and made sure she had diarrhoea tablets with her at all times.
She told the BBC: "I was sceptical about the therapy at first and could not understand how changing my mindset could change my bowels.
"But one of the most helpful things was understanding the strong link between how you think and how your body reacts.
"Now when I have nervous moments I don't dwell on them, I don't worry about it being something more sinister any more and I understand what is going on."
'Unhelpful adaptations'
The trial involved 558 people who had long-standing IBS, with symptoms despite medication and lifestyle advice.
- A third of people had telephone-based therapy (eight one-hour sessions speaking to a therapist, alongside their usual, standard treatment)
- Another third were offered web-based therapy (eight modules of interactive, online CBT and five half hour-sessions with therapists over the phone)
- The rest had standard treatment alone (such as anti-spasm medications and life style advice)
Both web and telephone therapy covered a number of topics, including detailed information on how the gut works, what IBS is, how to spot unhelpful behaviour and how to change and develop stable, healthy eating habits.
At the end of 12 months, researchers found patients who had had either therapy reported fewer symptoms, more ability to manage work and relationships and less anxiety and depression than people on standard treatment alone.
Lead researcher Dr Hazel Everitt told the BBC: "What often happens when we have chronic conditions that impact on our ability to get on and do what we want in our lives, is that we adapt and try and live our lives despite the problem and sometimes the adaptations that we make in the long term are unhelpful.
"An example might be that if you are concerned about your bowels you might be checking where the toilets are.
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