Chronic Constipation in Adults


Constipation is common.  Up to 30% adults will seek advice from a doctor in their lifetime with constipation.  But what is constipation?  It is not abnormal not to pass stool every day, or even second or third day!  In fact, normal is between 7 times in one day, to once in 7 days!

Constipation is defined as straining, and struggling to pass hard or lumpy stools with or without a feeling of inability to clear the rectum when passing stools.  There is no “number of stools per week” in the definition.


Common causes for constipation include:


  • Low fibre intake
  • Dieting
  • Fluid depletion
  • Anxiety, depression, anorexia

Pelvic Floor

  • Pelvic floor disynergy
  • Painful anorectal conditions


  • Diabetes
  • Hypercalcaemia (high calcium levels)
  • Hypothyroidism (under active thyroid)
  • Neurological diseases


Why do people get constipated  (Pathophysiology)

People with constipation can be divided into 2 broad categories namely

1. Slow transit constipation

(Where faeces moves slowly through the colon)


2. Obstructive defecation

(where the function of the rectum and pelvic floor is defective, and one cannot evacuate the rectum effectively)

Even though there is a clear division between these to groups, we often see some overlap between the two. The majority of people suffering from constipation will have predominantly obstructive defecation, with a component of slow transit, or vice versa.

Pure slow transit constipation is extremely rare, and the majority of people seeking help for constipation have predominantly obstructive defecation.


What tests should be done for Constipation?

A thorough physical examination is always needed, including vaginal and rectal examinations.

Although colonoscopy is often the first investigation that patients are referred for, or even request themselves, it adds little in finding the cause for constipation in a patient who has been struggling with constipation for years.  It is, however, very useful when there has been a change in your bowel habits, for instance if there has been a recent onset in constipation.  It is impossible to tell what the contractility and function of the colon is like while doing a colonoscopy.

To exclude underlying diseases that can cause constipation, one must do a set of blood tests once.  These tests will test your thyroid function, calcium levels, kidney function and blood counts.

In order to distinguish between slow-transit constipation and obstructive defecation, we do a colonic transit study (“pellet study”).  With this simple test, we give you small pellets to ingest, which will show up on X-rays.  We do X-rays on day 3, 5 and 7 after taking the pellets, ant this will show us how the pellets (and food) move through your gut.

Other tests may be needed and will be requested in specific instances, including a defecating proctogram, anorectal manometry etc.


How is constipation treated?

By the time a patient is referred to a specialist Colorectal Surgeon or Gastroenterologist, he or she has often tried almost all remedies and has lost faith in all of them.  The problem is, that most patients have used the treatments incorrectly and therefore did not experience any benefit.

We can divide treatment for constipation into 3 categories:

Bulk formers – Substances (usually water soluble dietary fibre) that increase the bulk of undigested material in the rectum

Osmotic substances – Acts by keeping water in the colon, thereby keeping the stools soft

Stimulants – Acts by increasing contractility of the entire gut, including the colon.

Bulk formers and osmotic substances are often referred to as stool softeners.


Category of Laxative


Bulk formers Psylum HuskFybogel OrangeAgiobulkNormacol
Osmotic Substances MovicolLaxetteLacsonDuphelacMilk of Magnesia


All bowel preparation medicines and Fleet

Stimulants SennaSoflaxDulcolaxLaxaBlack Forrest

Aloe products

Combination Bulk formers with Stimulants AgiolaxNormacol Plus

As some people have to use medication to control blood pressure or sugar, many people require regular medication to treat constipation.  It is not abnormal to “need something to pass stool”.

All patients, regardless if they have obstructive defecation or slow-transit constipation, require a stool softener (osmotic substance or bulk former or booth) on a daily basis.  My personal preference is to start with Movicol 1 sachet in the morning before breakfast, but any of the stool softeners (or combination of them) can be used.  Sometimes it is necessary to use stool softeners before breakfast and supper, every day.  It is important to note that this medication does not make you want to pass stool, it merely keeps the bowel motions soft, to prevent straining and hard lumpy stools.  All these medications are extremely safe and have no side effects.  They do not get absorbed from the gut, and therefore has no effects on the rest of the body.

Some patients will require a stimulant laxative regularly or just as needed, when the stool softeners do not result in passing a stool.  Stimulant laxatives can have side effects if they are used in overdose.  Their use should therefore be limited to “when needed” use.  There is absolutely NO evidence that stimulant laxatives damage the colon or “make the bowel lazy”.  It also does not lead to cancer or a higher chance to develop cancer!  Some people, especially those with predominantly slow-transit constipation, will need stimulant laxatives on a daily basis, together with the stool softeners.


Obstructive defecation

By far the most people who suffer from constipation have predominantly obstructive defecation.  These patients complain that they do not get the urge to go, or when they go, nothing happens.  They will also often experience a feeling that they cannot get everything out.  The process of defecation is a very complex, well-timed process that happens spontaneously.  Unfortunately in some, the muscles involved in defecation do not all work in sync, resulting in obstructive defecation.  The patient does not know that defecation is “out of sync”.  As the problem lies in the pelvic floor, taking excessive laxatives often does not work, and when it works, it leads to diarrhoea.

The best strategy to manage this problem is to use a stool softener (or combinations of stool softeners) every day, and then to use a suppository (like Dulcolax Suppositories) every second or third day, if you have not passed a stool yet by using the stool softeners alone.  Suppositories or enemas are much more effective in these patients than oral laxatives and stimulants.

In a few circumstances referral to a pelvic floor physio will be needed for Biofeedback.  Biofeedback is the name of a treatment modality where the pelvic floor is trained and “tuned” to work in unison.  Surgery is almost never indicated in obstructive defecation.


Slow transit constipation

Pure slow transit constipation is rare.  If you have an element of slow-transit constipation, regular use of stimulant laxatives like Senna, together with daily stool softeners is often needed.  Agiolax or Normacol plus are combination preparations of bulk formers and stimulants that are easy to use.  In a very small minority of patients with pure slow-transit constipation, a colectomy may improve their symptoms, but can be associated with significant other problems.



Constipation is common and to have to use something on a daily basis to keep stools soft is normal.  One des not have to pass a stool every day, or even every second or third day.  Colonoscopy is very seldom indicated as investigation in constipation and cannot give any indication of the function of the colon.  Surgery is almost never needed in managing constipation, and is best avoided.  A person suffering from constipation is not at a higher risk of cancers.


  1. McCullum I et al. Chronic constipation in adults. BMJ 2009;338:b831
  2. Chatoor, D et al. Constipation and evacuation disorders Best Practice & Research in Gastroenterology 2009;23:517