Symptoms and conditions
What is constipation? Causes, symptoms and when to see a specialist
Constipation means stools that are hard, difficult to pass or incomplete, whether or not they are infrequent. Most constipation responds to fibre, fluids, movement and better toilet habits, with a laxative where needed. When it does not, the usual reason is either a slow colon or pelvic floor muscles that tighten when they should relax. Both can be tested for and treated.
In short
- Constipation is defined by straining, hard stools and incomplete emptying, more than by how often you go.
- Medicines, low fibre intake and an underactive thyroid are common, correctable causes.
- Laxatives used as advised are appropriate treatment and do not damage the bowel.
- Constipation that does not respond to treatment should be tested for a pelvic floor problem.
What counts as constipation?
Doctors look for two or more of these, for three months:
- Straining
- Lumpy or hard stools
- A feeling of incomplete emptying
- A feeling of blockage at the anus
- Needing to use a finger or to press on the abdomen to pass stool
- Fewer than three bowel movements a week
In India, most healthy adults pass stool once or twice a day. A drop from your own usual pattern matters, even if you still go daily.
What are the types?
Normal-transit constipation
The colon moves at a normal speed, but the stool is hard and difficult to pass. This is the commonest type and overlaps with IBS.
Slow-transit constipation
The colon moves slowly, and there is little urge to go.
A pelvic floor (evacuation) disorder
The muscles of the pelvic floor and anus tighten during a bowel movement when they should relax. The main complaints are straining and incomplete emptying.
Constipation from another cause
Medicines, an underactive thyroid, diabetes, pregnancy, and occasionally a narrowing or growth in the bowel.
Which medicines cause constipation?
Strong painkillers, iron and calcium tablets, some antacids, some medicines for blood pressure, depression, allergies and bladder problems. Do not stop a prescribed medicine yourself; ask whether an alternative exists.
What should I try first?
Fibre, increased gradually
Vegetables, fruit, pulses, whole grains and millets. If food is not enough, add soluble fibre such as isabgol, starting with a small amount and building up over two weeks. Two kiwi fruit or a few prunes a day are effective for many people.
Fluids
Enough water to keep the urine pale. Fibre without fluid makes constipation worse.
Movement
A daily walk stimulates the colon.
Toilet routine
Sit after breakfast, when the colon is most active. Respond to the urge when it comes. Place a footstool under your feet, lean forward and do not strain. Limit the time to a few minutes.
A laxative, if needed
Osmotic laxatives, which hold water in the stool, are the first choice and are suitable for long-term use under medical advice. Stimulant laxatives are useful for short periods or occasional rescue.
When should I see a specialist?
See a doctor if you have
- Constipation that is new and persists beyond three weeks, especially after the age of 45
- Blood in the stool
- Weight loss or a low blood count
- Severe abdominal pain, swelling or vomiting
- Pencil-thin stools
- A family history of bowel cancer
See a specialist also when constipation has not improved after four to six weeks of the steps above.
Which tests find the cause?
- Blood tests for thyroid function, blood sugar, calcium and anaemia
- Colonoscopy when there are warning signs or screening is due
- Anorectal manometry with a balloon expulsion test, to see whether the pelvic floor relaxes properly
- A transit study, in which swallowed markers are followed on X-ray, to measure the speed of the colon
How is persistent constipation treated?
A pelvic floor disorder is treated with biofeedback, a training method in which sensors show you what the muscles are doing while a therapist teaches you to relax them. It works better than laxatives for this problem. Slow-transit constipation is treated with newer medicines that stimulate the colon or draw fluid into it. Surgery is needed only very rarely.
In my practice I also look at what lies behind the constipation: meal pattern, sleep, stress, thyroid function and the balance of gut bacteria, including methane-producing microbes, which are linked with slow transit.
Questions patients ask me
Will I become dependent on laxatives?
Used as advised, laxatives do not damage the bowel or cause dependence. Some people need them for the long term, in the same way that others need medicine for blood pressure.
Is it harmful not to pass stool every day?
No. Three times a week to three times a day is within the normal range, provided the stool is soft and passes without strain.
Does drinking more water treat constipation?
It helps if you are drinking too little, and it is needed for fibre to work. Beyond adequate hydration, extra water alone makes little difference.
Can constipation cause piles and fissures?
Yes. Straining and hard stools are the main cause of both. Treating the constipation is part of treating them. See piles and anal fissure.
Does long-standing constipation cause bowel cancer?
No. A pooled analysis of 28 studies found no increase in bowel cancer among people with constipation. Constipation that is new and persists after the age of 45 is different, and should be checked.
Sources
This page is written for patients and is based on the guidelines and studies below. It is for education and does not replace a consultation.
- American Gastroenterological Association and American College of Gastroenterology guideline on chronic constipation. Chang L et al. Gastroenterology. 2023. PubMed 37211380
- Indian consensus on chronic constipation in adults. Ghoshal UC et al. Indian J Gastroenterol. 2018. PubMed 30617919
- London classification for disorders of anorectal function. Carrington EV et al. Neurogastroenterol Motil. 2020. PubMed 31407463
- Rome IV criteria for bowel disorders. Lacy BE et al. Gastroenterology. 2016. PubMed 27144627
- Meta-analysis of constipation and bowel cancer. Power AM et al. Am J Gastroenterol. 2013. doi:10.1038/ajg.2013.52
- Review of myths about chronic constipation and laxatives. Muller-Lissner SA et al. Am J Gastroenterol. 2005. doi:10.1111/j.1572-0241.2005.40885.x