What are hives?
The medical name for hives is urticaria.
The red, irregularly shaped rash with a pale central bump (or wheal) that occurs in urticaria is itchy and tends to be fleeting, lasting minutes to a few hours before fading. Batches of the rash may reappear in different areas of the skin so that it seems as if it is migrating around the body.
Areas that are often affected include the face, trunk, arms and legs.
Why do we see a rash in urticaria?
Hives are the result of the release of various active chemicals and histamine into the bloodstream by mast cells. This results in inflammation and nerve stimulation. Blood vessels swell and become leaky and an itchy, raised red rash develops.
What causes urticaria?
Hives can appear due to an allergic reaction, a medication, insect bites or an infection. Sometimes it is caused by the body’s immune system, but often the trigger remains unclear and the hives seem to appear “out of the blue.”
Is urticaria common?
About 20 percent of people will experience hives at some time in their lives. It is more common in young adults and particularly in women.
What is CSU?
We call hives that recur without any discernable cause, and that come and go for more than 6 weeks, Chronic Spontaneous Urticaria (CSU).
Sometimes the rash is accompanied by areas of deep swelling (especially involving eyes, lips, tongue, throat, genitals, hands and feet) called angioedema.
It is important to be sure that there is no underlying medical condition causing the rash, so your doctor should be consulted.
CSU may continue unpredictably on a relapsing course for months to years before it settles.
Although it is not typically life-threatening CSU has a significant impact on quality of life. It affects daily activities, work, social interactions as well as sleep.
Triggers like scratching, sunlight, heat, cold, exercise, stress, alcohol, food additives and physical pressure may cause flares.
What tests should be done?
A careful history may uncover the cause of urticaria, but in most cases of CSU the cause is not clear.
Testing is aimed at excluding underlying medical conditions rather than uncovering a cause.
Can CSU be cured?
Treatment is aimed at the control of symptoms rather than cure.
Some relief of symptoms may be obtained by keeping cool and wearing loose, comfortable clothing that is made from soft, natural, breathable, fibres. Cool showers and soothing lotions may also afford temporary relief.
Oral antihistamines are helpful and the “first line” treatment for CSU. The newer non-drowsy antihistamines are best. Sometimes high does are required to control symptoms.
Cortisone may be necessary to control flares, but it should be avoided if possible, especially high doses for long periods of time, which can cause serious side effects.
Cortisone and antihistamine creams are unhelpful.
Other medications that may be helpful include certain anti-acids with an anti-histamine effect (the H-2 blockers), leukotriene modifiers, immune suppressants and an antibody called omalizumab. These are generally only used if anti-histamines have failed.