Skin inflammation

Skin inflammation is the redness, warmth, swelling, itching or pain that develops when the immune system responds to irritation, allergy, infection or injury in the skin.

It underlies many named conditions: eczema and atopic dermatitis, contact dermatitis from an irritant or allergen, psoriasis, acne, hives from mast cell activation, rosacea and sunburn. The process involves immune cells in the skin releasing cytokines and histamine, blood vessels widening, and nerve endings becoming more sensitive, which is why inflamed skin itches and hurts. Acute inflammation resolves once the trigger is removed; chronic inflammation persists or recurs and can thicken and darken the skin over time.

Dermatologists assess it by examining the pattern and distribution of the rash, asking about exposures and family history, and sometimes performing patch testing or a skin biopsy. The skin has its own endocannabinoid system, with cannabinoid receptors in keratinocytes, sebaceous glands, hair follicles and immune cells, and cannabidiol applied to skin has been studied in laboratory models and small human studies for inflammatory skin conditions. That evidence is preliminary, and no cannabinoid has an approved dermatological use.