What causes blisters on the skin?

Common triggers include friction, heat, sun exposure, contact with an irritant or allergen, eczema, and certain viral illnesses. The location, distribution, discomfort, and other symptoms help distinguish among them.

A blister exactly where footwear or a tool rubbed suggests friction. Blisters on red skin after intense sunlight fit a more severe sunburn. Itchy patches appearing after a new cosmetic, metal, glove, or cleaning product can occur with contact dermatitis.

Small, deeply seated, itchy blisters along the fingers, palms, or soles can occur with dyshidrotic eczema. Chickenpox can present with crops of itchy blisters in different stages, while shingles can present with painful grouped blisters in a band on one side of the body. Appearance alone cannot always confirm the cause.

Stop the likely source of rubbing, heat, or product exposure. Wash gently, pat dry, and cover a vulnerable blister with a clean non-stick dressing. Leave the blister roof in place when possible because it shields the tender skin underneath.

If it opens by itself, let the fluid drain, avoid peeling attached skin, and replace the dressing when wet or dirty. Do not deliberately open an unexplained cluster, especially when infection may be possible, because fluid can spread some illnesses to other skin or people.

Seek prompt medical assessment for blisters near the eyes, inside the mouth, or on the genitals; widespread blistering; severe pain; fever or feeling very unwell; rapidly spreading redness; warmth, swelling, pus, or red streaks. Blisters after a new medicine also need urgent assessment.

Get emergency help if blistering accompanies trouble breathing, facial or tongue swelling, faintness, extensive skin peeling, or difficulty drinking. People with diabetes, poor circulation, or reduced immunity should arrange early review for blisters on the feet or signs of infection.

Ask what features point to friction, allergy, eczema, a burn, or infection; whether the blister fluid could be contagious; which dressing is suitable; and whether any medicine or skin product should be stopped. Mention recent sun exposure, illness, travel, new medicines, and products that touched the area.