What causes constipation?

Constipation can have many causes and sometimes, there’s no single or obvious cause. Here are some of the most common causes of constipation:

• Lack of fibre in the diet (fruit, vegetables, or cereals)
• Not drinking enough water
• Too many caffeine-based drinks
• Too much alcohol can cause constipation
• Lack of movement
• A change in your diet or usual routine
• Constipation is common in pregnancy and for 6 weeks after
• Feeling stressed, anxious, or depressed
• Some medicines and other products can cause constipation, such as antacids, iron supplements, even some painkillers. If you think your medication is causing your constipation, speak to your GP for advice.

There are also medical conditions that can cause constipation, such as:

• Irritable bowel syndrome (IBS)
• Piles
• Narrowing of the bowel (strictures)
• Anal fissures (small tears)
• Bowel inflammation
• Pelvic floor damage
• Myotonic dystrophy and other muscle conditions
• Diabetes
• Conditions affecting the nervous system (such as strokes, multiple sclerosis, Parkinson’s disease)
• A spinal cord injury

There isn't always a single or obvious cause, this is what doctors call functional constipation, it's split into three types:

• Normal transit: Waste is not slowed as it travels through the bowel. This is the most common.
• Slow transit: Waste slows down as it travels through the large intestine.
• Outlet delay: When the muscles in the pelvic floor contract rather than relax when trying to open your bowels.

You may also see the terms faecal loading or impaction; this describes a situation in which the bowel is overloaded, and natural emptying becomes unlikely.