I was asked to write an article for a pediatric publication on hives (Contemporary Pediatrics, May 2000). I began the article with the following statement...."Children who suffer form urticaria (hives), especially chronic urticaria, deserve all the sympathy, support, and empathy that those who care for them can muster." To continue....."It is difficult to describe the discomfort, disability, and emotional distress caused by urticaria to those who have never experienced the disorder themselves. Not only does the child feel miserable due to the disease process itself; they may also suffer from the side effects of therapy. The extensive evaluations performed in pursuit of a cause for the hives, the pokes, the prods, the time spent in the doctor's office- add to the misery, as do worried parents who fear something is terribly wrong with their child." My stand has not changed since then.
What is a hive?
There are a few key features about hives that may distinguish this skin reaction from a number of other reactions. A hive is a well-circumscribed or well-defined raised, fleeting area of swelling on the skin. The size of the hives can be a fraction of an inch to many inches in diameter. These spots almost always itch. There is also the tendency for them to come and go in crops. The usual length of time that any one spot will remain on the skin is 24 hours. Circle a spot and look at it a day later. That particular area should clear in a day. Rarely, will the spots stay for as long as two days. If they last longer, then it is not typical hives and may be associated with inflammation of blood vessels or vasculitis. Also, in simple or typical hives the skin should be clear after the spot disappears. There are more serious variations of hives where there is actual bleeding into the skin leaving a mark for many days.
Facts about Hives
When hives occur on most days for eight or more weeks, it is referred to as "chronic". Episodes lasting less than eight weeks would be "acute" hives. When chronic urticaria is diagnosed, it should be somewhat reassuring that in half of the affected children, the illness will go away in about a year.
About 0.1% of the population has urticaria. It is more common in adults and more common in females. The earliest reported case of hives was in a one-month old infant.
Hives may be accompanied by angioedema or swelling of the deeper tissue of the skin. Angioedema usually does not itch. It is seen more frequently around the eyes, lips, tongue, hands, and feet. Those children who have hives and this type of swelling tend not to resolve the condition so quickly. It has been reported that 75% will continue to swell and have hives for 5 years.
What causes a hive?
The list of things that can cause hives is miles long and most probably every laboratory test that medicine can offer has been done in pursuit of a cause.
The following is a short list of general causes for hives:
Physical hives - due to:
- Mold spores
Non-allergic reactions - due to:
- Food additives
- Idiopathic- when no cause is found
Hives can be caused by a number of mechanisms- the classic allergic mechanism involving IgE, by activation of a part of the immune system called complement, by direct stimulation of cells, and by alterations of proteins by non-steroidal anti-inflammatory agents (aspirin).
All too often a food is suspected as the cause, especially in chronic urticaria. Food may account for only as much as 5% of cases of acute hives and in these situations, the patient and the family can easily see the cause and effect relation. Foods are a rare cause of chronic hives. Poorly documented case reports have suggested that caffeine, sulfites, monosodium glutamate (MSG) and nickel as causative agents. As advocates for children, we must be very careful regarding food claims and the need for elimination diets or rotational diets. These tend to have mystical appeal.
We must insist on strong evidence before embarking on dangerous and dark path of food allergy and hives.
Hives can also be due to contact with the skin. These spots occur only where the offending agent touched the skin.
Infections have long been associated with those who have chronic hives. Almost any type of infection- viral, bacterial, fungal, and parasitic has been associated with hives.
There are a number of popular notions that hives may be due to dyes, preservatives, antioxidants, flavor enhancers, and naturally occurring salicylates. These are referred to as pseudo-allergens. They may be the cause, but unfortunately there are no "tests" other than a challenge. The mechanism by which the hive is caused by these agents is not IgE mediated and cannot be assessed by skin testing.
A Practical Approach to the Evaluation of Hives
As with anything in medicine, a careful history and physical examination is essential. This is the most effective "test" your doctor can do. Testing beyond this is all based on what the story is and what is discovered on the examination.
For the most part, the evaluation is done to be sure nothing else is associated with the occurrence of the hives.
Skin testing for hives has a very low rate of return and should only be performed to support a clinical impression. Perhaps in 9% of patients will a test for allergy discover a cause and it is only in those cases where the history supported the result.
If the lesions are persistent or have associated color change, then consultation with a dermatologist should be considered.
When to see a specialist?
Those who have peanut induced or latex induced hives should see an allergist. If there is a poor response to treatment or if angioedema accompanies the hives, then a visit to allergy is necessary. If the hives are accompanied by other complaints, then a visit is encouraged. Also, any child or family who has concerns and desires a thorough evaluation would be welcome in our clinic.
Avoidance! This is a major theme in the world of allergic disorders. If a cause can be determined, then avoidance can be attempted.
Medications- antihistamines are the most important medications to use for hives. The itch should respond, however sometimes the redness will remain.
There are a large number of antihistamines to work with. Some may cause sedation; others may work better for certain types of hive.
Infrequently, a second antihistamine is added. This is frequently an antihistamine that is used to treat excessive stomach acid. It has been found that certain combinations of histamine type 1 and histamine type 2 receptor blockers offer relief. In the most sever cases steroids may be used.
Finding the cause is difficult in chronic urticaria. In acute urticaria, families are pretty good at making their own diagnosis as to cause. Evaluations for the most part are performed to exclude other disorders associated with hives.
Medications control symptoms, they are not a cure.