What causes crusting skin?

A small crust can form after scratching, a bite, a popped spot or another break in the surface. Atopic dermatitis may ooze and then crust when inflamed skin is scratched. Impetigo commonly presents with moist sores that develop a yellow-golden crust, often around the nose or mouth, and can spread through contact. Eczema herpeticum can cause clusters of painful, rapidly appearing blisters or punched-out sores with crusting and requires prompt assessment.

Colour, tenderness, speed of spread and the skin beneath the crust matter. A crust is a visible result of fluid drying; it does not identify the cause by itself.

Wash your hands before and after touching the area. Clean gently with lukewarm water, pat dry and avoid picking or forcibly lifting the crust. Keep towels, razors and cosmetics separate if infection is possible, and wash fabrics that touch a weeping lesion. Use only treatments intended for that area unless a clinician advises otherwise.

Arrange medical advice if crusting is spreading, recurrent, painful, weeping or accompanied by worsening redness. Seek prompt care for fever, facial or eye involvement, rapidly multiplying blisters, severe tenderness, or sores in someone with eczema. Urgent assessment is especially important when a lesion changes quickly or you feel generally unwell.

Ask whether the crust is more consistent with dermatitis, impetigo or a viral infection; whether a swab is needed; and how to clean and cover the area safely.