Hives (Urticaria) is an allergic affection of the skin characterized by raised, well-circumscribed areas of erythema and edema affecting the dermis and epidermis with associated pruritis.
It may be:
- Acute with a duration of less than 6 weeks; or
- Chronic with a duration greater than 6 weeks
There are several different types of Hives (Urticaria) such as:
Acute Urticaria: This type clears off within six weeks. The cause or triggering factor is usually identifiable. The commonest causes are foods, medicines, latex, infections, insect bites. At times, some internal disease may also trigger it.
Common foods such as nuts, chocolate, fish, tomatoes, eggs, berries, soy, wheat, and milk are known to trigger attacks. Certain food additives and preservatives are also known triggers.
Common medicines that trigger Hives (Urticaria) are aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs such as Ibuprofen), high blood pressure drugs (ACE inhibitors), or painkillers.
Chronic Urticaria and/or Angioedema: This type of urticaria extends beyond six weeks.
In this type, the cause or trigger is usually more difficult to identify. The triggers are usually similar to those of Acute urticaria. Additional causes can include autoimmune disorders, chronic infections, hormonal disturbances, and cancers.
- Physical Urticaria: This type is caused by direct exposure to physical causes that stimulate the skin. Some of these causes include cold, heat, vibration, pressure, sun exposure, exercise, sweating, etc.
- Dermatographism: These Hives (Urticaria) are usually the result of vigorously scratching, stroking, rubbing or slapping the skin. They can occur along with other types of Hives (Urticaria).
- Hereditary Angioedema: This type has a genetic predisposition and is passed on through families. It is characterized by swelling particularly of the face and airways. There may be associated abdominal cramping.