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.
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:
How often should we poo?
- 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
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.