Ulcer
A break in the skin or a mucous membrane that fails to heal normally.
What it means
An ulcer is a defect in a surface — skin or mucous membrane — extending through its full thickness and failing to heal. A shallower defect is an erosion.
Common types:
- Peptic ulcer — in the stomach or duodenum, usually from Helicobacter pylori or anti-inflammatory medicines
- Venous leg ulcer — from poor venous drainage, typically around the ankle
- Arterial ulcer — from poor arterial supply, typically on the foot and painful
- Pressure ulcer — from sustained pressure over a bony prominence
- Aphthous ulcer — the common mouth ulcer
In practice
Described by site, size, depth, edge and base — features which help distinguish causes. A rolled or everted edge raises concern about malignancy.
Treatment differs fundamentally by type: compression helps venous ulcers and is dangerous in arterial ones, which is why assessment of the blood supply comes first.
Why it matters
Any ulcer persisting beyond three weeks warrants assessment, particularly in the mouth, on the genitals, or on sun-exposed skin, where cancer must be considered.
A painless genital ulcer is characteristic of syphilis and is easily dismissed because it does not hurt and heals by itself.
Clinically reviewed by Dr Mohammad Zubair Khan, GMC 7563469
Last reviewed
August 30, 2026