Constipation Red FlagsNew constipation over 50, blood in stool, significant weight loss, family history of bowel cancer, or constipation with abdominal mass: these require urgent investigation (FIT test / 2-week wait referral).
Common Causes
| Cause | Examples | Treatment |
|---|---|---|
| Dietary / lifestyle | Low fibre, low fluid, inactivity | Fibre 30g/day; 1.5–2L fluid/day; exercise |
| Medications | Opiates, antidepressants (TCAs), calcium channel blockers, iron, antacids | Review medications; osmotic laxatives |
| Hypothyroidism | Constipation + weight gain + fatigue | TSH + treat with levothyroxine |
| Hypercalcaemia | Constipation + confusion + 'stones, bones, groans' | Calcium + PTH |
| IBS-C | Chronic bloating, abdominal pain, altered stool | Low-FODMAP; linaclotide; biofeedback |
| Slow transit constipation | Very infrequent motions; functional | Prucalopride; biofeedback |
| Bowel cancer | New onset; changed habit; rectal bleeding | Urgent FIT test and referral |
Laxative Types
| Type | Examples | Mechanism | Best For |
|---|---|---|---|
| Bulk-forming | Ispaghula husk (Fybogel) | Increase stool bulk + water retention | First line; mild constipation |
| Osmotic | Macrogol (Movicol), lactulose | Draw water into colon | Chronic constipation; opioid-induced |
| Stimulant | Senna, bisacodyl | Stimulate bowel wall contractions | Short-term; breakthrough constipation |
| Secretagogues | Linaclotide, lubiprostone | Chloride channels → water secretion | IBS-C; chronic idiopathic |
Fibre and Fluid TogetherAdding fibre without increasing fluid can worsen constipation. Aim for 30g fibre AND 1.5–2L fluid daily. Soluble fibre (oats, linseeds, psyllium) is more effective than insoluble (bran) for constipation.
When is constipation serious?
When associated with: unexplained weight loss, rectal bleeding, family history of colorectal cancer, new constipation in someone over 50, or a palpable abdominal mass. These need urgent investigation.
Is it safe to use laxatives long-term?
Osmotic laxatives (macrogol) are safe for long-term use. Bulk-forming laxatives are safe. Stimulant laxatives should generally be used short-term, though senna is used chronically in palliative care.
Does constipation cause bowel cancer?
No. Constipation does not cause bowel cancer. However, new onset constipation in someone over 50 can be a symptom OF bowel cancer, which is why it needs investigation.
What foods help constipation?
Prunes (contain sorbitol: natural osmotic laxative), kiwi fruit (actinidin enzyme improves gut motility), linseeds (soluble fibre), oats, and legumes. Drinking warm water or coffee in the morning also stimulates bowel motility.
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Medical Disclaimer: This page is for general education only and does not replace professional medical advice. Always consult a qualified healthcare provider.