Urticaria, also known as hives, is a skin disorder characterized by wheals, which are raised skin lesions with well-defined margins of redness and swelling, often associated with itchiness. This condition can be acute or chronic, wherein the former lasts for up to 6 weeks and the latter persists for more than 6 weeks. Acute urticaria develops and fades within hours after exposure to inciting agents, and episodes often persist for days. It is most often due to a reaction to foods, medications, chemicals, insect bites, infections, physical stimulants, or chronic inflammatory disease.
Hives result from the release of histamine from mast cell granules, which can be immune or non-immune mediated. An immune-mediated release of histamine is most often due to an immunoglobulin E (IgE)-mediated response against a foreign substance perceived by the body as dangerous. A non-immune-mediated release of histamine is due to chemicals that can directly induce degranulation of mast cells. Urticaria most often affects individuals between ages 20 and 40, although individuals of all age groups can be affected.
In children, allergic reaction to food is one of the major considerations in acute urticaria. The most common known foods that can cause an allergic reaction are peanuts, eggs, and seafoods such as fish and shellfish. Medications that usually cause acute urticaria are penicillin, aspirin, sulfa-based drugs, nonsteroidal anti-inflammatory drugs, opioids, angiotensin-converting enzyme (ACE) inhibitors, polymyxin B, and diuretics. Ammonium persulfate, which is found in hair chemicals, latex, and intravenous radiocontrast media, is an example of a chemical that can cause acute urticaria.
Viral infections are the most common infection that can cause acute urticaria. Examples are hepatitis B and C infections. Physical stimulants that can cause acute urticaria include cold, sunlight, pressure, water, and vibration. Examples of chronic inflammatory diseases that can cause acute urticaria are systemic lupus erythematosus and rheumatoid arthritis.
Diagnosis is usually established by a complete thorough history and physical examination. Imaging studies and skin biopsy are only done if indicated by the history. Management of the disease consists of identifying its etiology and, if possible, controlling its severity, relieving itchiness and discomfort, and educating the patient. Prevention of future episodes of acute urticaria can be done by patient education and avoidance of the identified etiology. Relief of itchiness and discomfort can be achieved through the use of first- or second-generation antihistamines with or without histamine 2 (H2) antagonists, tricyclic depressants, leukotriene receptor antagonists, or glucocorticoids.