What causes a sore that will not heal?

A wound can persist when friction, scratching, picking, pressure, or an unnoticed foreign body repeatedly disrupts new skin. Infection may cause increasing redness, warmth, swelling, drainage, odour, or tenderness. Diabetes, reduced blood flow, swelling, smoking, poor nutrition, or medicines that affect immunity can slow repair. Some persistent sores are skin cancers: [Basal Cell Carcinoma](/conditions/basal-cell-carcinoma/) may resemble a shiny or scabbed spot, while [Squamous Cell Carcinoma](/conditions/squamous-cell-carcinoma/) can form a rough, crusted, tender, or bleeding area. [Keratoacanthoma](/conditions/keratoacanthoma/) is another growth that can develop quickly and needs review. A sore’s appearance cannot establish its cause.

Gently rinse the area, pat it dry, apply a clean dressing, and reduce rubbing or pressure. Avoid hydrogen peroxide, harsh antiseptics, picking, and unplanned steroid or antibiotic creams. Note when it began, whether it bleeds or returns, and any change in size, border, colour, pain, or drainage. Arrange a clinical examination; a swab, circulation check, or biopsy may be needed depending on the findings.

Seek prompt medical assessment for any sore that keeps reopening, enlarges, crusts repeatedly, bleeds with little contact, becomes painful, or develops a firm edge. Get urgent help for spreading redness, severe pain, fever, pus, red streaks, numbness, or a wound on a foot with diabetes or poor circulation. Do not wait for a sore to become dramatic before having a persistent lesion examined.

What features suggest infection, irritation, or a skin growth? Does the area need a swab or biopsy? Could circulation, diabetes, or a medicine be slowing healing? How should I dress it? Which changes require urgent review?