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Urticaria


By Dr. Adrian Yong Sze Wai (Consultant Dermatologist) | Tue Oct 25, 2016 3:03pm

URTICARIA
LEARN ABOUT URTICARIA, A CONDITION THAT CAN AFFECT YOUR QUALITY OF LIFE AND IS OFTEN MISTAKEN TO BE DUE TO “ALLERGY”.

Urticaria, also known as hives affects around one in five people at least once during their lifetime. Urticaria appears as red or white circular swelling of skin, known as wheals. These circular swollen skin areas are often itchy or burning in nature.

Urticaria can appear anywhere on the skin. Individual wheals normally disappear on their own within 24 hours without leaving any marks on the skin. If the wheals are burning in nature, lasts longer than 24 hours and leaves bruise marks on the skin afterwards, urticarial vasculitis should be suspected. Urticarial vasculitis requires urgent medical attention for further investigations.

Angioedema consists of deeper swelling in the skin, which may take more than 24 hours to clear. It is not itchy and often involves the eyelids, lips and mouth. Sometimes, the swelling of angioedema may affect the tongue or throat, causing difficulty with breathing or swallowing. This can be alarming but is rarely life threatening.  Some people develop urticaria and some develop angioedema and some suffer from both.

The most common form of urticaria is called spontaneous urticaria. In this type, no cause is usually identified and often patients have urticaria and angioedema occurring together. Spontaneous urticaria with or without angioedema is usually divided into ‘acute’ and ‘chronic’ forms. In ‘acute’ urticaria, the episode lasts up to six weeks. Chronic urticaria, by definition, lasts for more than six weeks.Urticaria is caused by the release of histamine from cells in the skin called mast cells.

A cohort study performed in a reputable cutaneous allergy centre in Berlin reports that the association between chronic urticaria and proven food allergy occurs in only 2 out of 100 people.

Potential triggers for acute urticaria include the following:

• Infection e.g. upper respiratory tract infection
• Contact with allergen
• Sun exposure
• Specific food e.g. alcohol/cheese or medicine
• Cow’s milk allergy in babies
• Bee and wasp stings
• Shellfish, nuts, apples and peaches

Almost any medicine can cause urticaria, but painkillers (especially aspirin, ibuprofen, diclofenac), antibiotics (especially penicillin group antibiotics), blood products and vaccinations are commonly reported as causes.

Angioedema, in particular, can be caused by a type of drug (ACE inhibitors) used to lower blood pressure and protect the heart.

In some patients with chronic spontaneous urticaria, the release of histamine from skin mast cells is triggered by factors circulating in the blood, such as antibodies directed against their own mast cells, a process known as autoimmunity. A skin test or blood test maybe performed to detect the presence of this condition.

Urticaria is not hereditary although a rare form of angioedema (hereditary angioedema) can run in families. In a small percentage of people, foods, colouring agents and preservatives appear to worsen urticaria, and it might be helpful to identify these by keeping a food diary. These substances can be omitted from the diet to see if the condition improves, and later reintroduced to confirm whether they are the cause of the urticaria. However, as urticaria fluctuates frequently, this is not always accurate.

Urticaria is often thought to be related to allergy, but in fact, allergy is not the commonest cause of urticaria.  Second generation non-sedating oral antihistamines are safe and often effective in managing urticaria when taken regularly. The older generation antihistamines tend to cause drowsiness and does not allow for safe operation of machineries or vehicles. In fact the older generation antihistamines and even some of the second generation antihistamines are not deemed safe for pilots to consume prior to flying, as ruled by the United States Federal Aviation Administration. In the presence of autoimmunity, stronger immunosuppressive medications maybe used under close specialist supervision to provide relief.

 

 






 

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