Mucus in stool

Mucus is a clear, white or yellowish jelly-like substance made by the lining of the bowel to keep it moist and to help stool pass smoothly, so a small amount in the stool is completely normal and usually goes unnoticed. It becomes worth attention when there is clearly more of it than usual, when it persists, or when it comes with other symptoms. Irritable bowel syndrome (IBS) is a common cause of passing visible mucus, often alongside abdominal pain, bloating and a changeable bowel habit, but without inflammation or bleeding. Increased mucus can also reflect genuine inflammation of the bowel, as in the inflammatory bowel diseases (ulcerative colitis and Crohn's disease), where it is often mixed with blood and diarrhoea — a combination that always needs looking into. Gut infections can temporarily increase mucus, as can constipation, anal problems like fissures or piles, and, less commonly, bowel polyps or a tumour. So the key is the company it keeps: mucus alone, in small amounts, is usually harmless, whereas mucus with blood, persistent diarrhoea, pain, weight loss or a lasting change in bowel habit points more towards inflammation or another cause that should be assessed.

• Irritable bowel syndrome (IBS) — a common cause of visible mucus, with pain and altered habit but no inflammation or blood.
• Inflammatory bowel disease (ulcerative colitis, Crohn's) — mucus often mixed with blood and diarrhoea; needs investigation.
• Gut infections (gastroenteritis) — a temporary increase.
• Constipation — can be associated with more mucus.
• Anal problems — fissures or haemorrhoids.
• Bowel polyps or, uncommonly, a tumour — especially with other alarm symptoms.

A little mucus with no other symptoms usually needs no tests. When it is persistent, increased, or comes with diarrhoea, blood, pain or weight loss, a targeted approach helps. Faecal calprotectin is the key test: it distinguishes inflammation of the bowel (as in inflammatory bowel disease, where it is raised) from a non-inflammatory cause such as irritable bowel syndrome (where it is normal). CRP is a general marker of inflammation, and a full blood count and ferritin check for anaemia if there has also been bleeding. Stool tests for infection and, where indicated, a colonoscopy complete the picture. Mediora.AI can surface a raised calprotectin and CRP that point towards an inflammatory bowel cause; persistent mucus with other symptoms is assessed by your doctor.