Urticaria, also known as “hives” or “wheals”, is due to fluid leaking out from blood vessels in the skin. This causes swelling on the surface of the skin. Urticaria is characterized by red, itchy wheals on the skin’s surface.
Angioedema happens when this leak happens in the deeper layers of the skin.
Angioedema appears as large swollen areas under the skin.
Angioedema can occur around the eyes, on the lips and tongue, and even internally in the windpipe.
Urticaria and angioedema commonly occur together, but may also occur separately.
What Causes Urticaria and Angioedema?
Hives and angioedema occur when certain cells in the body (called mast cells) release chemicals (such as Histamine and Bradykinin) into your bloodstream.
These chemicals make your small blood vessels enlarge and become leaky. Fluid then leaks out from the vessels into the surface of the skin.
Chronic hives can be troublesome to live with, but typically disappears with time and appropriate treatment.
Hives and/ or angioedema may be caused by:
- Food or medication allergies.
- Your physical environment such as heat, cold, sunlight, exercise, or even pressure on the skin.
- Certain medical conditions such as thyroid disorders, blood disorders (e.g. leukemia or lymphoma) and certain autoimmune diseases.
In cases of young patients who develop angioedema alone without hives, it might be due to a rare disease called Hereditary Angioedema (HAE), especially if other family members are affected.
How are Urticaria and Angioedema Diagnosed?
You may need to undergo some tests to diagnose the cause of the urticaria/ angioedema.
These tests may include:
- skin prick testing to help diagnose food allergies
- blood tests to screen for thyroid or blood disorders or HAE
However, the majority of hives or angioedema cases have no identifiable cause. This occurs in 40 to 50% of all cases of urticaria and angioedema.
How are Urticaria and Angioedema Treated?
1) Avoid the Allergen
If your urticaria and angioedema are due to an allergy to food or medication, then avoiding the allergen is necessary to prevent relapses.
2) Reduce Exposure to Physical Triggers
If your urticaria is triggered by a physical factor (such as cold or exercise), you may need to modify your activities to reduce exposure to these factors.
For chronic urticaria, oral antihistamines are the most commonly used medications to treat this condition. These medications block the release of histamine from mast cells. You may need to take these antihistamines on a daily basis, up to twice daily.
You may also be given other drugs to:
- Block the action of histamine (e.g. Famotidine)
- Modify the immune system's response (e.g. Ciclosporine)
- Or a subcutaneous injection of an antibody called Omalizumab once every 4 weeks
Severe cases of angioedema will require an Epinephrine autoinjector for emergency use. This is especially so if your windpipe has been affected and causes breathing problems.