At a glance
Most fissure information focuses on constipation as the primary cause — and it is the most common one. But diarrhoea can also cause anal fissures, and this fact is often overlooked. People whose fissures are related to loose stools rather than hard stools sometimes find that standard advice (add more fibre, take stool softeners) makes their situation worse rather than better.
This guide explains how diarrhoea leads to fissures, why the management approach differs, and what to consider if loose stools are part of your fissure picture.
How diarrhoea causes fissures
Several mechanisms connect diarrhoea to anal fissure development:
Frequency of bowel movements
More bowel movements mean more passages through the anal canal. Each passage is an opportunity for the lining to be irritated or damaged. People with diarrhoea may have five, ten, or more bowel movements in a day — the cumulative effect on the anal tissue is significant.
Acidity
Loose stools tend to be more acidic than well-formed stools. The digestive process has not fully completed, and the resulting stool can be chemically irritating to the sensitive anal lining. People describe a burning sensation that accompanies diarrhoea-related fissure pain.
Wiping trauma
Frequent bowel movements mean frequent wiping. The mechanical friction of toilet paper — often applied urgently and repeatedly — damages the skin and lining around the anus. This is one of the most direct causes of diarrhoea-related fissures.
Urgency
The urgency that accompanies diarrhoea can cause people to strain or push, even with loose stools. This straining increases pressure on the anal canal and can contribute to tearing.
Moisture damage
Persistent moisture from frequent loose stools breaks down the skin around the anus, making it more vulnerable to tearing. The combination of moisture, acidity, and friction creates conditions where fissures are likely.
When diarrhoea-related fissures happen
Common contexts people describe:
- Gastroenteritis — a stomach bug that causes days of diarrhoea
- Antibiotic use — disrupting gut bacteria and causing loose stools
- IBS flare-ups — particularly diarrhoea-predominant or mixed-type IBS
- Food intolerances — triggering episodes of diarrhoea
- Inflammatory bowel disease — Crohn’s disease or ulcerative colitis
- Stress-related bowel changes — anxiety and stress can trigger loose stools
- Post-surgical — some procedures affect bowel function temporarily
Why standard advice can miss the mark
Most fissure guidance assumes constipation:
- “Increase your fibre” — but too much fibre with diarrhoea can make stools looser
- “Take stool softeners” — counterproductive when stools are already too soft
- “Drink more water” — important for hydration but does not address the root cause
- “Eat more fruits and vegetables” — some of these can worsen diarrhoea
People with diarrhoea-related fissures describe frustration when they follow standard advice and their symptoms get worse. Recognising that the cause is diarrhoea rather than constipation is the first step to appropriate management.
Managing diarrhoea-related fissures
Address the underlying cause
The most important step is identifying and managing why the diarrhoea is occurring:
- If it is IBS — working with a clinician on IBS management
- If it is dietary — identifying trigger foods through an elimination approach
- If it is medication-related — discussing alternatives or probiotics with your prescriber
- If it is infectious — treating the infection and supporting recovery
- If it is IBD — managing the underlying disease
Protect the area
While addressing the cause:
- Water-based cleaning — a peri bottle or bidet instead of wiping
- Barrier cream — to protect the skin from acidic stool contact
- Gentle patting — if wiping is necessary, use soft, unscented toilet paper and pat rather than rub
- Sitz baths — warm water after bowel movements to soothe the area
Adjust the stool
When the goal is to firm up stools rather than soften them:
- Soluble fibre — such as psyllium husk, which can add bulk to both hard and loose stools
- Dietary adjustments — reducing foods that trigger loose stools
- Probiotics — particularly after antibiotic-related diarrhoea
- Discuss with your clinician — they may recommend specific approaches based on the underlying cause
Standard fissure care still applies
Some elements of fissure care apply regardless of the cause:
- Sitz baths for comfort and sphincter relaxation
- Prescribed topical treatments if recommended
- Adequate hydration — particularly important with diarrhoea to prevent dehydration
- Monitoring for signs that the fissure is or is not healing
When to seek care
Contact your clinician if:
- Diarrhoea has been persistent and the fissure is not improving
- You are unsure whether your fissure is related to diarrhoea or constipation
- Standard fissure advice seems to be making things worse
- Heavy or persistent bleeding that does not settle
- Fever or signs of infection
- Symptoms that are worsening despite self-care