One in five individuals will develop urticaria, or hives at some point in their lives. Most cases of urticaria are self-resolving and of short duration. Chronic urticaria occurs when the rash has been continuously or intermittently present for 6 weeks or longer. In most cases of chronic urticaria, no underlying cause is found, and the condition is then called chronic idiopathic urticaria. Chronic urticaria is more common in women than men. Urticaria can be associated with significant psychological, social and occupational distress.
The pink, swollen rash of urticaria is generally itchy. The wheal and flare appearance of urticaria is caused by the release of histamine. Individual lesions fade within 24 hours, but new lesions may develop while older lesions are resolving. If each lesion of urticaria lasts longer than 24 hours, the rash may actually represent a more serious condition such as urticarial vasculitis.
There are numerous allergic and non-allergic causes of urticaria, including:
- Foods and food additives
- Medications – most commonly to penicillin
- Contact allergy (to environmental exposure, e.g. latex)
- Insect bites
- Non-allergic mediators such as aspirin and radiocontrast media
- Medical causes such as viral and fungal infections
- Physical causes such as cold, pressure, heat, water
- Idiopathic (unknown, which accounts for the majority of chronic idiopathic urticaria)
If you present with chronic urticaria, your physician may order a series of blood tests to investigate the underlying cause. These studies, however, often are normal. Chronic urticaria may recur frequently and persist for years, often causing a great deal of distress. Your dermatologist or allergist, however, can help you manage your symptoms.
If the identifiable trigger of urticaria is a certain food, medication or exposure, then that item is withdrawn or avoided. Most cases of urticaria respond to medications. The most widely used agents in the treatment of urticaria include:
- First generation H1 antagonists including diphenhydramine (benadryl), hydroxyzine (Atarax) and chlorpheniramine
- Second generation H1 antagonists including cetirizine (Zyrtec), levocetirizine (Xyzal), loratadine (Claritin), desloratadine (Clarinex) and fexofenadine (Allegra)
- H2 antagonists including cimetidine and ranitidine.
- Short course of systemic corticosteroids (more appropriate for acute urticaria). Due to side effects, long-term use should be avoided in chronic urticaria.
- Adrenergic agents such as epinephrine if urticaria is accompanied by a life-threatening condition such as anaphylaxis or swelling of the respiratory tract (angioedema).
The outlook for individuals with acute urticaria is excellent. It may resolve with symptomatic treatment or avoidance of identifiable causes.