Constipation: causes and symptoms

What is constipation?

Constipation refers to abnormally infrequent bowel motions and/or pain or difficulty when passing small, hard stools. A bowel motion every day is not always necessary. People’s bowel habits differ, and some people have a bowel motion only every second or third day — or longer.

Constipation is not the same as irregular bowel habits — it is when you have to strain to pass a bowel motion, which is usually hard.

Constipation symptoms

Symptoms of constipation include:

  • reduced frequency of bowel motions (fewer than 3 per week);
  • difficulty and straining when passing bowel motions;
  • passing small, hard, lumpy stools; and
  • a feeling of incomplete evacuation or inability to empty the rectum.

You may also feel bloated or have abdominal pain. Occasionally, some people complaining of diarrhoea may in fact have ‘overflow’ diarrhoea as a result of constipation.

Haemorrhoids (enlarged, congested veins in the rectum or anus) and anal fissures (small tears in the skin of the anus) are complications that can result from constipation.

Constipation causes and risk factors


If you don’t drink enough fluids or get enough fibre in your diet, you may be more prone to constipation. Not getting enough physical activity can also cause constipation.

Ignoring the urge to defecate on a repeated basis can also cause constipation. It’s important to listen to your body and go to the toilet when you get the urge.

Sometimes a change in your daily routine – such as going on holiday – can trigger constipation.


Constipation is a possible side effect of some medicines and supplements, including:

  • opioid painkillers (e.g. codeine);
  • some antihistamines;
  • certain antidepressants;
  • diuretics;
  • some medicines used to lower blood pressure and treat heart disease (e.g. verapamil);
  • antacids that contain aluminium or calcium;
  • calcium supplements; and
  • iron supplements.

Overuse of certain laxatives (medicines used to treat constipation) can also worsen constipation.

Gastrointestinal tract problems

Constipation can be a symptom of many different bowel conditions including:

  • irritable bowel syndrome;
  • coeliac disease; and
  • diverticular disease.

Constipation can also be caused by a partial obstruction of the bowel due to:

  • bowel tumours (polyps and bowel cancers);
  • tumours in the abdomen that obstruct the bowel from the outside; and
  • adhesions (bands of fibrous scar tissue that may result from previous surgery).

Other conditions

Constipation can sometimes be caused by an underlying condition. Conditions that can cause constipation include:

  • pregnancy;
  • depression;
  • hypothyroidism (underactive thyroid);
  • diabetes;
  • pelvic floor muscle problems; and
  • neurological conditions (such as Parkinson’s disease, spinal cord injuries and stroke).

Tests and diagnosis

Your doctor will ask about your symptoms and perform a physical examination. Depending on your history and physical examination findings, they may recommend tests such as:

  • blood tests;
  • an abdominal X-ray;
  • colonoscopy (where a lighted, flexible tube is used to examine the inside of the rectum and large bowel); and/or
  • tests to evaluate the function of the lower bowel.

When should you seek medical advice?

You should seek medical advice if:

  • constipation is accompanied by vomiting;
  • there has been associated weight loss;
  • bowel motions are very dark and tarry looking, or contain blood;
  • the constipation has been recurrent, persistent or is worsening;
  • there is abdominal pain or bloating;
  • you are having to use large amounts of laxatives;
  • constipation alternates with diarrhoea;
  • you are generally feeling tired and unwell;
  • you have a fever;
  • constipation has continued longer than 7 days; or
  • you have a family history of bowel cancer, inflammatory bowel disease or other significant gastrointestinal problems.

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