Reference
The Bristol scale, without the jargon.
Seven types, from hard and lumpy to liquid. The scale gives a subject few people enjoy discussing a matter-of-fact vocabulary — at an appointment, in rehab, and for yourself.
Why have a scale at all?
"It was sort of firm" gets you nowhere in a consultation. So in the mid-nineties Stephen Lewis and Ken Heaton at the University of Bristol devised a simple classification into seven shapes. It is now used worldwide — in clinics, in research, and in patient groups.
The real value lies less in any single day than in the pattern. A type 6 after a heavy evening means little. Two weeks of mostly type 1 is a pattern worth discussing.
The seven types
From 1 to 7 it gets softer.
Separate hard lumps
Like nuts, hard to pass. The stool spent a long time in the colon and had a lot of water drawn out of it. Usually involves straining and a feeling of not being finished.
Marked constipationSausage-shaped but lumpy
The lumps from type 1 pressed together. Firm, often bulky, frequently uncomfortable. The line between this and type 1 is blurry.
Mild constipationSausage-shaped with cracks
Formed, but with visible cracks on the surface. Passes without much effort and counts as unremarkable.
Normal rangeSmooth and soft, like a snake
The type most clinicians name as the target: formed, soft, no straining. Water balance and transit time are in step.
Normal rangeSoft blobs with clear edges
Passes easily but no longer holds together. Often a sign of too little fibre — or simply that things moved faster than usual.
Tending to looseFluffy pieces with ragged edges
Mushy, with no fixed shape. The contents moved quickly, so little water was reabsorbed. Common with infections, intolerances, or certain medication.
Mild diarrhoeaLiquid, with no solid pieces
Entirely liquid. If it lasts several days, the loss of fluid and salts is the real problem — especially in children and older people.
DiarrhoeaWhat shapes the shape
The biggest factor is how long the contents stay in the colon: the longer, the more water is drawn out and the firmer it gets. That in turn depends on fluid intake and fibre, movement, daily rhythm, and whether you answer the urge or routinely suppress it.
Then there is medication — opioids and some iron supplements firm things up, magnesium and certain antibiotics loosen them. And stress, which pushes many people in either direction.
Variation is normal. Almost nobody has type 4 seven days a week.
When to seek medical advice
The scale describes a shape; it does not make a diagnosis. With any of these signs, the matter belongs in expert hands rather than in a log:
- Blood in the stool — bright red, or black and tarry
- A change that lasts longer than three weeks
- Unintended weight loss
- Severe or persistent abdominal pain
- Fever alongside diarrhoea
- Symptoms that wake you at night
- Bowel cancer or inflammatory bowel disease in the family
- New changes from around the age of 50
When in doubt, ask early rather than late.
A special case: neurogenic bowel
After a spinal cord injury, or with multiple sclerosis or spina bifida, the bowel behaves differently because the control pathway through the spinal cord is disrupted. The Bristol scale still works as a description, but the target differs: people using digital stimulation or irrigation often deliberately aim for a slightly firmer stool because it is easier to manage. What is right for you belongs in a conversation with your care team.
Important with a spinal cord injury at or above roughly T6: a blocked bowel can trigger autonomic dysreflexia — a dangerous blood pressure crisis with a pounding headache, sweating and flushing above the level of injury. This is an emergency. Sit upright, loosen tight clothing, look for the cause, and get medical help.
Why it pays to write it down
Memory gets it wrong — you remember the striking days and forget the ordinary ones. Two or three weeks of recorded types build a picture that holds up in a consultation, and shows whether a change actually helped.
Bladder & Bowel Manager turns that into one tap per entry and shows the trend across weeks. Everything stays on your device.