Clinical Immunology and Allergy | Auckland | Te Toka Tumai | Te Whatu Ora

Hives/Urticaria - Causes and Treatment

What is urticaria?
Urticaria (also known as hives) is an itchy rash that can appear like welts, which comes and goes in a seemingly unpredictable fashion.  

Sometimes, if you scratch the skin, you may notice it comes up in a raised red line.  This is called dermatographism.

Urticaria is actually quite common with one out of three people getting it at some stage in their life.

The skin swelling seen in urticaria is due to the release of chemicals such as histamine from mast cells and basophils in the skin, which causes small blood vessels to leak. The welts can be a few millimetres or several centimetres in diameter, coloured white or red, often surrounded by a red flare, and frequently itchy. Each wheal (or weal) may last a few minutes or several hours, and may change shape. Wheals may be round or form rings, a map-like pattern or giant patches.

The surface wheals may be accompanied by deeper swelling of eyelids, lips, hands and elsewhere. The deeper swelling is called angioedema and may occur with or without urticarial wheals (10%).

Did you know?  80% of cases of hives occurring in adults are not due to allergy
This is particularly true for hives that are recurrent or chronic (occurring on a daily basis).  Hives due to allergy more often comes on in sudden discreet attacks after food only.  Non-allergic hives can come and go any time of the day, and often occurs overnight or first thing in the morning too. 

Causes of chronic or recurrent hives
Recurrent or chronic hives can be caused by different factors.  Sometimes one of these factors can cause urticaria by itself, but sometimes a combination of multiple factors is needed. 

Also, these factors can be intermittent, causing hives only sometimes.  This can make it confusing when trying to identify the cause.  Here is a list of some common causes:

• Autoimmune causes - this is where the body's immune system tends to activate itself and cause the hives.  This is quite a common cause of hives.  It is important to note that it is very rare that this signifies any significant other autoimmune disease though.  A thyroid test should be done however.
• Medications - commonly codeine or non-steroidal anti-inflammatory drugs NSAIDS like ibuprofen, diclofenac, Voltaren, Nurofen and aspirin.  Many cough and cold remedies can contain NSAIDs. One in three adults with recurrent hives will intermittently and unpredictably react to NSAIDs and aspirin.  If this happens all NSAIDs and aspirin must be avoided.  Patients may need an alternative for analgesia, and an Arcoxia challenge can be considered.
• Stress and any extraordinary or emotional recent events in a person’s life may trigger or maintain hives.
• Infections including viruses and bacteria.  This often causes hives during or after the infection for a few days.
• Time of menstrual cycle.
• Physical triggers may include pressure, cold, heat, sunlight, exercise and, rarely, water. Dermatographism or "skin writing" is marked by the appearance of weals or welts on the skin as a result of scratching or firm stroking of the skin. Seen in 4–5% of the population, it is one of the most common types of urticaria, in which the skin becomes raised and inflamed when stroked, scratched, rubbed, and sometimes even slapped.

Treatment of chronic or recurrent urticaria (hives)
The first step is diagnosis of the cause, which involves accurate, detailed discussion between doctor and patient, with particular emphasis on the multiple factors listed above.  Sometimes, just understanding the role of these multiple factors with intermittent effects, helps a patient understand the nature of hives and can provide a feeling of control over the situation.

Antihistamines

• For patients with recurrent or even daily hives it is best to take regular antihistamines.  This can be once daily, but often twice daily is needed.  They should be non-sedating such as loratadine or cetirizine.  If hives occur mainly at night or early morning, they should be taken before bed.  Sometimes higher doses of regular antihistamines are required for urticaria than the doses used in other conditions.  In general, these higher doses are well tolerated and side-effects are rare.

Avoid the causes

• Looking at the factors in the list above to see if any of these can be modified.

Does chronic urticaria go away?
For people who have chronic urticaria (hives every day for more than six weeks), this problem always goes away eventually.  It does tend to take months to completely resolve.  50% of long term cases resolve by one year and 30% resolve the year after.  Milder cases will often go away sooner.

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