Doctors and the public are at odds over the symptoms of constipation, leaving some people without the advice or treatment they need, researchers say.
While medics think infrequent bowel movements are an important sign, less than a third of the public does, a study found.
The King's College London team said a new definition for constipation was needed, based on patient experiences.
"This shows the poo taboo is over," charity Guts UK said.
Constipation is a very common condition, affecting around one in seven people who are otherwise healthy.
It means having difficultly opening or emptying the bowels, and passing stools - but the way it is diagnosed varies widely.
The researchers say this list of six groups of symptoms could help form a new definition of constipation:
- abdominal discomfort, pain and bloating - clothes not fitting as well as usual
- rectal discomfort - bleeding from pushing too hard, pain or burning sensation in the anal area
- infrequent bowel movements and hard stools - normal can range from three times a day to three times a week
- sensory dysfunction - not having the urge to go or a sense of incomplete evacuation
- flatulence and bloating - noisy or smelly wind
- faecal incontinence - uncontrolled leakage or rectal bleeding
What is this list based on?
The researchers surveyed 2,557 members of the public, 411 GPs and 365 gastroenterology specialists and published the results in the American Journal of Gastroenterology.
They found that what most people think of as symptoms of constipation aren't included in any official diagnostic criteria.
- spending a long time on the toilet unable to pass a stool
- needing to use laxatives
While most people who said they had constipation had symptoms that matched the official criteria, one in three 'healthy' patients didn't recognise their symptoms of constipation at all.
And doctors and the public don't seem to agree on the signs to look out for either, the study found.
Medics placed lots of emphasis on infrequent bowel movements, as a symptom, but only half of people who said they had constipation actually experienced this symptom.
What do the researchers say?
Dr Eirini Dimidi, study author from King's College London, said: "Our research may indicate that people who seek help for symptoms of constipation don't always have them recognised, diagnosed or managed."
She said constipation was usually caused by a lack of fibre or fluid in the diet but it could also be a sign of another underlying problem, such as bowel cancer, diverticular disease or coeliac disease.
Dr Dimidi said it was "always important to consult your doctor if you experience gut symptoms".
What about other experts?
Listening to what patients say about constipation is important, said Julie Harrington, from charity Guts UK.
"Patients are the experts, by experience, and when they come together with specialists, that's the sweet spot."
Not all constipation is the same, and different people have different symptoms, she added.
"Bowel problems are less likely to be picked up than other problems because people wait 6-12 months out of fear and embarrassment.
"You have to tune into your body."
How often should we poo?
This is difficult to answer - it can vary dramatically from person to person.
In the study, seven bowel movements a week was the average among people who weren't constipated.
But experts say three bowel movements a day to three a week qualifies as normal.
So you need to know what's normal for you - and then look out for changes.
What are the treatment options?
Most people recognise the problem themselves and try to solve it by increasing the fibre in their diet and drinking more fluid, according to NHS advice.
Fibre is present in wholegrain bread, wholegrain pasta, fruit, nuts, pulses and cereals.
Taking more exercise and eating regular meals can also help.
You can buy laxatives from the chemist if diet and lifestyle changes aren't working.
But it's important to see your GP if the problem persists, and you have other symptoms.