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# Reflux oesophagitis: what acid does to the squamous lining

- Lesion

When stomach acid repeatedly flows back up, the lining of the lower oesophagus thickens, gets inflamed and may erode.

Updated Nov 12, 2026

## Key points

- Main mechanism: transient lower sphincter relaxation; worsened by hiatal hernia, obesity, pregnancy, alcohol, tobacco, delayed gastric emptying and raised abdominal pressure.
- Histology: intraepithelial eosinophils, basal zone hyperplasia, elongated lamina propria papillae; neutrophils mean more severe injury.
- Mild disease may show only redness with normal histology.
- Complications: erosions and ulcers, bleeding, stricture and Barrett oesophagus.
- Heartburn and regurgitation, worse after meals and lying down; can mimic angina.

## What it is

Gastro-oesophageal reflux is the commonest cause of oesophagitis. Transient relaxations of the lower oesophageal sphincter, mediated by the vagus and triggered by gastric distension, let acid and pepsin (sometimes bile) bathe the squamous epithelium. The epithelium responds by proliferating and recruiting inflammatory cells, and in some patients it erodes, scars or changes into columnar (Barrett) mucosa.

## Structure

- Endoscopy: hyperaemia, then linear erosions above the junction.
- Basal zone (proliferative) layer expanded beyond its normal share of the epithelium.
- Lamina propria papillae reaching up toward the surface.
- Scattered intraepithelial eosinophils; neutrophils and erosions in severe cases.

## Step by step

- The lower sphincter relaxes transiently or is weak, or a hiatal hernia removes the crural pinch.
- Acid and pepsin flow back onto squamous epithelium.
- Surface cells are injured and shed; basal cells proliferate to replace them.
- Inflammatory cells (eosinophils, then neutrophils) enter the epithelium.
- Repeated injury leads to erosion, fibrotic stricture or columnar metaplasia.

## Clinical notes

- Sliding hiatal hernias (junction pulled into the chest) are common and favour reflux; paraoesophageal hernias can strangulate.
- Endoscopy is kept for symptoms that resist acid suppression or for suspected complications.

## Memory aid

Acid upstairs: the basement layer thickens, the papillae climb, and eosinophils drop in.

## Test yourself

Think of the answer, then tap the question to see it.

## What is thought to be the main mechanism of gastro-oesophageal reflux?

Transient, vagally mediated relaxation of the lower oesophageal sphincter, often triggered by gastric distension.

## What are three histological features of reflux oesophagitis?

Basal zone hyperplasia, elongated lamina propria papillae and intraepithelial eosinophils (neutrophils in severe cases).

## Which long-term change of reflux carries a cancer risk?

Barrett oesophagus, intestinal-type columnar metaplasia that can progress to adenocarcinoma.

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## Elsewhere in DurgiPedia

- [Esophagus and the Barrett change](https://durgical.com/en/histology/esophagus-and-the-barrett-change/)
- [Swallowing and esophageal motility](https://durgical.com/en/physiology/swallowing-and-esophageal-motility/)

## Connections

## Related 5

- [Barrett oesophagus](https://durgical.com/en/general-pathology/barrett-oesophagus/)
- [Eosinophilic oesophagitis, and how it differs from reflux](https://durgical.com/en/general-pathology/eosinophilic-oesophagitis-and-how-it-differs-from-reflux/)
- [Oesophageal obstruction: stenosis, webs, rings, diverticula](https://durgical.com/en/general-pathology/oesophageal-obstruction-stenosis-webs-rings-diverticula/)
- [Oesophageal adenocarcinoma: from Barrett to invasive cancer](https://durgical.com/en/general-pathology/oesophageal-adenocarcinoma-from-barrett-to-invasive-cancer/)
- [Patterns of acute inflammation: serous, fibrinous, purulent, abscess, ulcer](https://durgical.com/en/general-pathology/patterns-of-acute-inflammation-serous-fibrinous-purulent-abscess-ulcer/)

## Related conditions 5

- [Gastro-oesophageal reflux disease (GERD)](https://durgical.com/en/conditions/gastro-oesophageal-reflux-disease/)
- [Hiatal hernia](https://durgical.com/en/conditions/hiatal-hernia/)
- [Barrett oesophagus](https://durgical.com/en/conditions/barrett-oesophagus/)
- [Obesity](https://durgical.com/en/conditions/obesity/)
- [Systemic sclerosis (scleroderma, including CREST)](https://durgical.com/en/conditions/systemic-sclerosis/)

[← All of general pathology](https://durgical.com/en/general-pathology/)

Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.

Sources: [Gastroesophageal Reflux Disease (GERD)](https://www.ncbi.nlm.nih.gov/books/NBK554462/) (StatPearls (NCBI Bookshelf), 2025); [Esophagitis: MedlinePlus Medical Encyclopedia](https://medlineplus.gov/ency/article/001153.htm) (MedlinePlus, US National Library of Medicine, 2025).

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Representative model, for educational purposes only.

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License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/general-pathology/reflux-oesophagitis-what-acid-does-to-the-squamous-lining/