Hudreaktion

Hudreaktion, literally “skin reaction” in German, refers to any change in the skin that results from exposure to a variety of stimuli, including allergens, irritants, medications, infections, or physical factors. It encompasses several clinical patterns such as dermatitis, urticaria, angioedema, and various drug eruptions.

Common forms include allergic contact dermatitis, caused by sensitizers like nickel, fragrances, or preservatives, and irritant dermatitis from soaps, solvents, or detergents. Urticaria presents with transient, itchy wheals and sometimes angioedema. Drug eruptions can range from mild maculopapular rashes to more severe reactions. Photodermatitis arises from an interaction between light and certain chemicals or medications. Other less frequent patterns include fixed drug eruption and erythema multiforme.

Causes are diverse and include environmental exposures, cosmetics, occupational allergens, medications, infections, and physical factors such as temperature or friction. Pathophysiology varies by pattern: allergic contact dermatitis is typically a Type IV hypersensitivity reaction, while urticaria involves mast cell degranulation and histamine release. Some reactions are mediated by other immune pathways or are non-immune irritant responses.

Diagnosis relies on history and clinical examination, supported by tests such as patch testing for contact allergens or skin prick testing for immediate hypersensitivity. In uncertain cases or to rule out other conditions, a skin biopsy can be informative.

Treatment focuses on removing or avoiding the trigger, using topical corticosteroids or calcineurin inhibitors for inflammation, and employing oral antihistamines for itching. Severe or widespread reactions may require systemic steroids or specialist care. Prognosis varies with the underlying cause; many hudreaktion episodes resolve with trigger withdrawal, while others may become chronic. Prevention centers on identifying and avoiding known triggers, particularly in occupational and cosmetic contexts.