Constipation is infrequent evacuation of the bowels, with difficulty and sometimes pain from passing hard stools.

Constipation is prevented by a diet high in vegetables and fibre. Failure to empty the bowels (defecate) at least once a day does not in itself pose any danger to health.

Many entirely healthy people defecate only once every two or three days, and some at even longer intervals. Some people have a bowel motion three times a day. All are normal. Constipation can be defined as the passage of hard stools less frequently than normal.

Causes

In a high proportion of cases the cause is purely dietary. However, there are other possible causes of constipation, including:
 

• Painful conditions affecting the anus and discouraging bowel-emptying, for example, piles
• Colon obstruction from a disease such as cancer
• Medication, including iron, codeine, some antacids with aluminium and opiate painkillers
• Depression
• Thyroid gland underactivity
• Lack of physical activity
• Inadequate fluid intake
• Pregnancy.

Note that iron pills will make the stools very black, as will bleeding from high in the intestine.

If constipation comes on for no obvious reason after a long period of normality, see your doctor without delay.

Treatment

The way to cure constipation is to ensure adequate bulk in the stools. This means a diet high in fruit, vegetables and bran-containing cereals. Bran is calorie-free, and takes up large quantities of water. Plenty of fluid should always be taken with the bran. This kind of regime will produce bulky, soft stools and regular motions.

If your doctor confirms that there is no serious cause for your constipation and diet doesn’t help, don’t use irritating or stimulant laxatives such as senna without medical advice. Stick to bulking agents like dietary fibre, bran, ispaghula husks or methylcellulose. An alternative is medication that draws water into the bowel (osmotic medication) such as lactulose or Epsom salts (magnesium sulphate). Occasionally a suppository or enema may be appropriate if oral treatment has not produced a bowel movement.

Constipation in pregnancy is a common complaint reported in 11–38% of pregnancies. Increasing dietary fibre in the form of wheat or bran fibre is the treatment of choice.

Avoid laxatives in children unless prescribed by a doctor.