Urticaria

Question 1

What is urticaria?
Associations?
Classifications?

Answer 1

Urticaria are also known as hives. They are small itchy lumps that appear on the skin. They may be associated with a patchy erythematous rash. This can be localised to a specific area or widespread. They may be associated with angioedema and flushing of the skin. Urticaria can be classified as acute urticaria or chronic urticaria.

Question 2

Pathophysiology urticaria?

Answer 2

Urticaria are caused the release of histamine and other pro-inflammatory chemicals by mast cells in the skin. This may be part of an allergic reaction in acute urticaria or an autoimmune reaction in chronic idiopathic urticaria.

Question 3

Causes of acute urticaria?

Answer 3

Acute urticaria is typically triggered by something that stimulates the mast cells to release histamine. This may be:

Allergies to food, medications or animals
Contact with chemicals, latex or stinging nettles
Medications
Viral infections
Insect bites
Dermatographism (rubbing of the skin)

Question 4

Chronic urticaria causes?

Answer 4

Chronic urticaria is an autoimmune condition, where autoantibodies target mast cells and trigger them to release histamines and other chemicals. It can be sub-classified depending on the cause:

Chronic idiopathic urticaria
Chronic inducible urticaria
Autoimmune urticaria

Chronic idiopathic urticaria describes recurrent episodes of chronic urticaria without a clear underlying cause or trigger.

Chronic inducible urticaria describes episodes of chronic urticaria that can be induced by certain triggers, such as:

Sunlight
Temperature change
Exercise
Strong emotions
Hot or cold weather
Pressure (dermatographism)
Autoimmune urticaria describes chronic urticaria associated with an underlying autoimmune condition, such as systemic lupus erythematosus.

Question 5

Management of urticaria?

Answer 5

Antihistamines are the main treatment for urticaria. Fexofenadine is usually the antihistamine of choice for chronic urticaria. Oral steroids may be considered as a short course for severe flares.

In very problematic cases referral to a specialist may be required to consider treatment with:

Anti-leukotrienes such as montelukast
Omalizumab, which targets IgE
Cyclosporin