What causes constipation?

The bowel absorbs water as stool moves through it. When movement is slow or stool lacks enough water and fibre, it can become hard, dry and difficult to pass. Travel, changes in routine, pregnancy, stress and repeatedly delaying a bowel movement can contribute.

Medicines such as some pain medicines, iron tablets and certain antacids can slow the bowel. Dehydration may make stools harder. Hypothyroidism can slow digestion. Pain from an anal fissure or haemorrhoids may make someone avoid passing stool, while diverticular disease can be associated with altered bowel habits.

Increase fibre gradually through vegetables, fruit, beans, whole grains and nuts, and drink fluids regularly unless a clinician has advised restriction. Gentle walking, a regular toilet routine and responding to the urge can help. A footstool may make a comfortable position easier.

If constipation began after a medicine, ask whether the dose or an alternative should be reviewed rather than stopping it alone. A pharmacist or clinician can recommend a suitable laxative when lifestyle measures are not enough. See [Constipation](/symptoms/constipation/) and [Nutrition Counselling](/treatments/lifestyle-and-wellness/nutrition-counselling/).

Arrange a review if constipation is persistent, recurrent, newly unexplained or accompanied by weight loss, tiredness, blood in the stool or a change in bowel pattern. Seek urgent care for severe or worsening abdominal pain, repeated vomiting, marked swelling, inability to pass stool and gas, or faintness. Read [Dehydration](/conditions/dehydration/) and [Anal Fissure](/conditions/anal-fissure/) for related concerns.

Ask whether a medicine, thyroid problem or another bowel condition could be contributing, how quickly to increase fibre, and which laxative is appropriate for you. Mention the timing of onset, stool appearance, bleeding, pain, diet, fluid intake and family bowel history.