Hives or urticaria are red or white raised itchy skin swellings that can change in size or shape over hours or days. Hives result from local dilation of capillaries in the skin that allows fluid to flow into the surrounding skin. This fluid collection results in the typical raised appearance of hives.
Who is likely to develop hives?
A chemical called histamine most commonly causes hives. If histamine is injected by needle into an adolescent’s skin, then it will produce what is termed the triple response: localized redness due to dilation of the blood vessels, a swelling or wheal due to leakage of fluid from the local blood vessels and a flare of redness that spreads beyond the swelling.
Histamine may be released into a teen’s body by a number of different stimuli. Under certain conditions that are listed below, circulating mast cells may release histamine into the surrounding tissue or circulation. If this occurs, then the triple response reactions may occur in susceptible individuals.
The causes of hives are many, and the following list is a partial classification of causes for hives. However, most adolescents will not develop hives in response to the following conditions:
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Foods: fish, shellfish, nuts eggs, strawberries and chocolate
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Food additives: salicylates, tartrazine dyes and benzoates
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Drugs: penicillin, aspirin and sulfa antibiotics
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Infections: infectious mononucleosis, intestinal worms, hepatitis B
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Inhalants: animal dander, house dust, volatile chemicals and aerosols
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Diseases: thyroid problems, rheumatic fever
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Physical stimuli: sun, cold, water, vibration and heat
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Contact stimuli: animals such as jellyfish, medications, chemicals, textiles, wood, saliva, cosmetics, perfumes and foods
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Hormones: pregnancy or premenstrual flare-ups
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Genetic: familial cold producing hives
What are the symptoms of hives?
Hives may be round or oval swellings that vary in size from 2-4 mm to the size of an entire extremity. They may be red or white in color or have variations with these two colors. Occasionally hives may coalesce to form a much larger appearing hive, and some hives are surrounded by a halo of different colored skin. Hives always itch. The itch may vary widely in its intensity. Thicker and deeper hives itch less than superficial hives since the swelling occurs in areas below the skin surface that have fewer nerves to convey the sensation of itch.
How are hives evaluated?
Adolescents with persistent hives should be evaluated. The evaluation could be done by a primary care clinician or by a skin specialist. If the clinician determines that the teen does have hives, then these are some of the steps that he or she may take in evaluation of the hives:
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History: what did the patient eat or drink recently; any travel history, exposure to chemicals or medications
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Physical examination: evaluate for infection
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Laboratory work: no routine studies usually done for new onset of hives
The cause of hives may be elusive since ingredients may be hidden in certain foods or products. Sometimes, hives occur quickly after exposure and occasionally they may occur days later and this adds to the difficulty in tracing the cause of the hives. Herbal medications may have ingredients that are unfamiliar to clinicians, so it is important to communicate to the clinician all medications that a teen has used prior to the onset of the hives. And it is important to remember that ingredients in illicit drugs may trigger hives in susceptible adolescents.
Hives that have been present on the teen for less than six weeks are termed acute. If hives are present more than six weeks, then this is termed chronic and often the cause of the hives is unclear. Evaluation for chronic hives is more extensive than the evaluation for acute hives. A complete medical history and physical examination is usually performed and this may also include a dental examination by a dentist. Laboratory studies could be ordered to elicit the cause of chronic hives and this could include tests for allergies, parasites, immune disorders, thyroid problems and chronic infections.
How are hives treated?
Adolescents with acute or chronic hives usually respond to medications called antihistamines. These medications control hives by inhibiting the dilation of capillaries and the leakage of fluid into the surrounding tissue. Antihistamines also moderate the itch.
There are a variety of antihistamines available. These include the so-called first generation antihistamines: diphenhydramine (Benadryl), hydroxyzine (Atarax) and chlorpheniramine (Chlor-Trimeton). The second-generation antihistamines include loratadine (Claritin) and cetirizine (Zyrtec). First generation antihistamines tend to produce more sedation as well as dry mouth, blurred vision, constipation and dizziness. Second generation antihistamines do not cross the blood-brain barrier so these antihistamines should not produce sedation.
Beside medications, removal of the cause for the hives should be part of the treatment plan. For example, if a teen develops hives to penicillin, then the penicillin medication should be discontinued.
How are hives prevented?
Avoiding the known cause of hives is important in their prevention. Teens may develop hives from the cold. This could result from exposure to a sudden drop in air temperature or from exposure to cold water. If this occurs, then prevention would include wearing appropriate clothing in cold weather including gloves or mittens, hats and scarves. For susceptible teens, cold-water exposure should also be avoided.
Sun exposure can cause hives in susceptible adolescents. This could be problematic during sunbathing during the summer or skiing in the colder months. Antihistamines, sunscreen or sun blocks and graduated exposure to increasing amounts of sunshine may prevent solar hives.
Some teens report hives to hair conditioners that may be used by girls with long hair. These hair products, termed protein hydrolysates, are used to repair hair. These products have ingredients such as collagen, keratin, elastin, milk, and wheat, almond or silk. Hair sprays that include methyldibromo glutaronitrile may cause hives in susceptible teens. Hives due to permanent waving have been noted rarely. If one of these products causes hives in the teen, then contact with the product should be avoided.
Related topics:
Allergies, antibiotics, dermatitis, hair care, hair dye, herbal remedies, skin disorders, sun safety, tanning salons,
