Allergic and irritant contact dermatitis of the scalp is experienced by millions of people every year. Contact dermatitis is characterized as an inflammatory, often itchy, condition caused by reaction of the skin after contact with a sensitizing external agent.
The classic example is the itchy and blistered skin that follows contact with poison ivy. Other agents causing allergic and irritant contact dermatitis range from:
- Workplace chemicals
Irritant contact dermatitis usually appears immediately or soon after contact with an irritant agent. Allergic contact dermatitis characteristically appears upon encountering an agent that previously came into contact with the skin; an allergic response usually requires sensitization by an initial encounter with the allergenic agent.
Hair dyes or ingredients of hair-care products such as straighteners, permanent wave solutions, tonics, etc., are the external agents most frequently responsible for allergic or irritant contact dermatitis of the scalp. While major manufacturers strive to eliminate any irritating or allergic potential from their hair-care products, some individuals may have skin characteristics that predispose them to inflammatory or allergic reactions to certain sensitizing agents. "Home-made" products such as lye-based hair straighteners are not safety tested and can have significant potential for causing contact dermatitis. Irritant contact dermatitis is characterized by inflammation and burning sensations soon after contact with an irritant agent. Severe, persistent inflammation may result in temporary or permanent hair loss. The condition usually resolves over time, after withdrawal of the irritant. Persistent dermatitis should be treated by a physician.
Allergic contact dermatitis can have varying presentations ranging from mild scalp inflammation to chronic eczema and involvement beyond the scalp to inflammation and edematous swelling of the face and neck. Unlike irritant contact dermatitis, allergic contact dermatitis can persist for days to weeks after withdrawal of the allergenic agent. Persistent allergic contact dermatitis requires medical treatment.
Diseases and Disorders of the Scalp