Understanding What Drives Diarrhoea &
Why the Nervous System Matters

Diarrhoea is often described as an infection or something you “ate,” but for many people it becomes a recurring or long-term pattern.

Diarrhoea is a symptom, not a diagnosis. It reflects how quickly food is moving through the gut, how well digestion is working, how balanced the microbiome is, and how the nervous system is regulating gut function.

For some, it appears as sudden urgency. For others, it is loose stools after meals, unpredictable bowel habits, or flares during stressful periods.

What Diarrhoea Really Is

In most cases, diarrhoea develops when gut motility becomes too fast or poorly regulated.

Common underlying contributors include:

  • heightened gut sensitivity

  • stress-driven acceleration of intestinal movement

  • low stomach acid or weak digestive enzyme output

  • bile acid imbalance

  • bacterial or parasitic overgrowth

  • post-infectious changes

  • inflammation or irritation of the gut lining

  • food intolerances or malabsorption

  • hormonal influences

  • side effects of medication

This is why anti-diarrhoeal medication alone rarely solves the problem long term.

The Gut–Brain Axis

Your gut responds immediately to signals from the nervous system.

When the body enters fight, flight, freeze or shutdown, intestinal movement often speeds up. This is part of the body’s threat response, but when it becomes chronic, it can lead to ongoing loose stools, urgency and fatigue.

Many people notice diarrhoea worsens during:

  • emotional stress or anxiety

  • pressure or conflict

  • busy or unpredictable schedules

  • poor sleep

  • long-standing tension patterns

For some, diarrhoea becomes one of the body’s clearest signs that it is operating under constant stress.

Why Common Diarrhoea Advice Falls Short

Avoiding certain foods, using anti-diarrhoeal medication, or following very restrictive diets can reduce symptoms temporarily, but they often fail to address:

  • why the gut is moving too quickly

  • why digestion is incomplete

  • why the microbiome is out of balance

  • or why the nervous system remains in a state of high alert

Without addressing these drivers, symptoms frequently return.

What Actually Helps Long Term

Lasting improvement comes from slowing and stabilising gut function while restoring digestive balance.

This often involves:

Supporting digestion
Improving stomach acid, enzyme output and bile regulation.

Normalising motility
Helping the gut return to a steady, predictable rhythm.

Balancing the microbiome
Addressing infections or overgrowth and rebuilding beneficial species.

Soothing the gut lining
Reducing inflammation and irritation.

Regulating the nervous system
Reducing chronic stress signalling and improving resilience.

Rebuilding food confidence
Identifying true triggers without unnecessary restriction.

When these layers are supported together, bowel movements often become more formed, more predictable and less urgent.

TLDR

What drives diarrhoea
Diarrhoea usually reflects overly fast gut movement influenced by digestion, microbial balance, inflammation, hormones and nervous system activity.

The role of the nervous system
Stress states can speed up intestinal movement and increase sensitivity, making diarrhoea persistent. Supporting nervous system regulation is often central to recovery.

In short
Diarrhoea is rarely just about food poisoning or infection. It is usually a motility–microbiome–nervous system pattern. When these systems are supported together, the gut can settle.

This is the Mind–Body–Biome approach.