Nässelfeber

Nässelfeber, or urticaria, is a common skin condition characterized by transient, itchy wheals (hives) on the skin, sometimes accompanied by swelling beneath the surface layer called angioedema. Each wheal typically lasts less than 24 hours, but new ones can appear as old ones fade. When symptoms persist for more than six weeks, the urticaria is considered chronic. Angioedema can occur with or without wheals and may involve the lips, tongue, or throat.

Causes and triggers vary. Acute urticaria is often related to infections, foods, medications (such as nonsteroidal anti-inflammatory drugs or antibiotics), insect stings, or physical factors. Physical urticarias are triggered by specific stimuli like cold, heat, pressure, or sunlight. Chronic spontaneous urticaria is frequently idiopathic, but autoimmune mechanisms and other underlying conditions (including thyroid disease) may contribute. In many cases no single trigger is identified.

Diagnosis is typically clinical, based on history and skin examination. Laboratory tests are not routinely required but may be used to evaluate persistent urticaria or to rule out other conditions. In chronic cases, tests might include complete blood count, thyroid function, or screening for related autoimmune conditions if indicated. If angioedema is present without hives, or if there is a suspicion of hereditary or acquired angioedema, specific tests are recommended.

Treatment focuses on symptom relief and trigger avoidance. First-line therapy consists of non-sedating second-generation antihistamines (for example cetirizine or loratadine). If control is inadequate, the dose may be increased up to fourfold. Additional options include H2 blockers, leukotriene receptor antagonists, and short courses of systemic corticosteroids for severe flares. Refractory chronic cases may benefit from omalizumab or, rarely, immunosuppressants. Emergency management is required for anaphylaxis or airway angioedema.