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# Blisters and erosions: pemphigus, pemphigoid and erythema multiforme

- Oral pathology

Blisters that break into raw areas in the mouth can be the first sign of serious immune skin diseases. Biopsy is the key test.

Updated Nov 12, 2026

## Key points

- Pemphigus often starts in the mouth.
- Pemphigoid scars the eyes: check them.
- Biopsy with immunofluorescence decides.

## What it is

Several immune-mediated diseases present with oral blisters and erosions. In pemphigus vulgaris, autoantibodies against desmoglein separate cells within the epithelium: blisters are fragile, so patients usually show painful erosions, and the mouth is often the first site, months before the skin. In mucous membrane pemphigoid, antibodies target the basement membrane: blisters are more tense, the gums peel (desquamative gingivitis) and scarring can affect the eyes and larynx. Erythema multiforme is an acute reaction, often after herpes simplex infection, with crusted, bleeding lips, widespread oral erosions and target lesions on the skin; Stevens–Johnson syndrome is a different, drug-induced and more severe disease.

## How to recognise it

- Pemphigus vulgaris: oral erosions first, positive Nikolsky sign, intraepithelial split.
- Mucous membrane pemphigoid: older adults, desquamative gingivitis, risk of eye scarring.
- Erythema multiforme: sudden onset, haemorrhagic lip crusts, target lesions, often after HSV.
- Stevens–Johnson syndrome and toxic epidermal necrolysis: recent new drug, fever, extensive skin and mucosal loss.
- Diagnosis: biopsy of perilesional tissue for histology and direct immunofluorescence.

## Differential and risks

- Persistent oral erosions treated for months as «aphthae» or «candidiasis» may be pemphigus.
- Pemphigoid with eye symptoms (gritty eyes, red eyes) needs urgent ophthalmology to prevent blindness from scarring.
- Stevens–Johnson syndrome is an emergency: stop the culprit drug and admit.

## Next step / Initial management

- Unexplained oral erosions for more than two to three weeks: refer for biopsy with direct immunofluorescence (oral medicine, dermatology).
- Suspected pemphigus or pemphigoid: refer promptly; pemphigoid with eye involvement needs urgent ophthalmology.
- Suspected Stevens–Johnson syndrome: stop new drugs, admit and refer urgently.
- Erythema multiforme: supportive care and pain relief; treat or suppress herpes if it triggers recurrences.

## Test yourself

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

## Where does pemphigus vulgaris often appear first?

In the mouth, as painful erosions, often months before skin lesions.

## Why must the eyes be checked in mucous membrane pemphigoid?

Because conjunctival scarring can lead to blindness.

## What infection commonly triggers erythema multiforme?

Herpes simplex virus infection.

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## Connections

## Related 3

- [Oral lichen planus](https://durgical.com/en/dentistry/oral-lichen-planus/)
- [Herpes in the mouth: primary gingivostomatitis and cold sores](https://durgical.com/en/dentistry/herpes-in-the-mouth-primary-gingivostomatitis-and-cold-sores/)
- [White and red patches in the mouth: approach](https://durgical.com/en/dentistry/white-and-red-patches-in-the-mouth-approach/)

## Related conditions 3

- [Pemphigus vulgaris](https://durgical.com/en/conditions/pemphigus-vulgaris/)
- [Mucous membrane (cicatricial) pemphigoid](https://durgical.com/en/conditions/mucous-membrane-pemphigoid/)
- [Bullous pemphigoid](https://durgical.com/en/conditions/bullous-pemphigoid/)

## In Pharmacology 1

- [Corticosteroids (glucocorticoids)](https://durgical.com/en/pharmacology/classes/corticosteroids/)

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Educational content; it does not replace assessment by a dentist or doctor and is not a clinical instruction. For facial or neck swelling with difficulty swallowing or breathing, a knocked-out tooth or bleeding that will not stop, go to an emergency department at once.

Sources: [Pemphigus Vulgaris](https://www.ncbi.nlm.nih.gov/books/NBK560860/) (StatPearls Publishing (NCBI Bookshelf), 2024); [Cicatricial Pemphigoid](https://www.ncbi.nlm.nih.gov/books/NBK526120/) (StatPearls Publishing (NCBI Bookshelf), 2025); [Erythema Multiforme](https://www.ncbi.nlm.nih.gov/books/NBK470259/) (StatPearls Publishing (NCBI Bookshelf), 2024); [Immune-Mediated Oral Mucosal Diseases](https://www.ncbi.nlm.nih.gov/books/NBK597383/) (StatPearls Publishing (NCBI Bookshelf), 2023).

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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/dentistry/blisters-and-erosions-pemphigus-pemphigoid-and-erythema-multiforme/