Types and Classification
TRIGGERS AND CAUSES
Urticaria or hives occur secondary to the activation of certain cells in the body’s immune system known as mast cells. Mast cells are commonly present in the skin, gastrointestinal and respiratory tract. In chronic urticaria, mast cell activation in the skin is triggered by the production of antibodies against the body’s own substances. Chemicals present in the mast cells like histamines are released into the skin, which can cause irritation of nerve endings resulting in localized itching. In addition, blood vessels expand and leak fluid, leading to redness and swelling. Chronic spontaneous urticaria is almost never allergic in origin. Various factors can trigger or worsen symptoms but are not the cause of urticaria itself. These include infections, medications like pain killers (aspirin, diclofenac, ibuprofen), stress, food like histamine rich foods, food additives like preservatives, color etc. Food induced worsening of symptoms are due to intolerance, and food allergy is rarely a cause of chronic urticaria. In most cases, no underlying cause can be determined.
TESTING
The diagnosis of chronic urticaria is based on symptoms, and further testing is not usually warranted. Basic tests may be done to determine the nature of the disease, especially in the presence of associated systemic symptoms, to rule out severe allergic reactions/anaphylaxis. Allergy testing for food is not indicated in patients with chronic spontaneous urticaria unless history suggests the immediate onset and recurrence of symptoms after a particular food.
TREATMENT
There is no cure for chronic urticaria at the current time, but symptoms can be controlled in most patients. The main aim of treatment is complete control over symptoms. The main treatment for chronic urticaria are antihistamines which are anti-allergy medicines. Non- sedating antihistamines (2nd generation antihistamines) are recommended, and dosage can be increased up to a maximum of 4 times the dose if symptoms are not controlled on single dosing. Biologic agents like omalizumab or immunosuppressive medications are added if antihistamines do not relieve symptoms. Although corticosteroids may be used for a short time during severe flares, steroids should not be used for long. If specific triggers like medications or food are identified, these should be avoided.