Skin Allergic Reactions
In an allergic reaction, the skin normally exhibits a reaction known as wheals, flares or a combination of both. Wheals are round or flat elevation of the skin that usually disappear in a few hours. Flares, on the other hand, are seen as reddening of the skin. Multiple eruptions of wheals are called hives or urticaria. Urticaria with edema (swelling of the affected area) is called angioedema.
What are some forms of allergic reaction?
Although allergic reactions are typically caused by an allergen, different people exhibit different allergic responses. Here are some examples:
Dermographism. When the skin is stroked rapidly with a solid object, a wheal rapidly appears at the site of contact. The wheal lasts for approximately half an hour and then spontaneously disappears. This is the most common type of physical urticaria.
Pressure urticaria. Swelling appears on areas of the skin a few hours after being subjected to sustained pressure, for example from shoulder straps and belts.
Cold urticaria. Wheals appear at the site of contact with a cold object. Potentially life-threatening if whole body is subjected to cold, for example during swimming.
Heat urticaria. Wheals appear after exposure to locally applied heat.
Solar urticaria. Allergic reaction occurs after exposure to the sun.
Contact urticaria. Allergic reaction occurs after coming into direct contact with an allergen.
Infections. Allergic reactions, including wheals and urticaria, may be a manifestation of a bacterial infection, for example hepatitis B or in respiratory tract infections in children.
Are laboratory tests necessary?
Clinical evaluation, including a comprehensive history and physical examination, is usually enough to establish presence of an allergic skin reaction. No specific laboratory tests are necessary for allergic reactions, although a doctor may request other tests in order to determine the presence of complications or other illnesses apart from the allergic reaction.
How are allergic reactions treated?
The best treatment for any allergic reaction is the removal of the cause. To that end, identification of the offending agent is very important. In acute cases of allergic reaction, H1-type antihistamine drugs are the first choice in their management.
Apart from avoidance of allergens and allergic-reaction medication, another important component in management of allergic skin reactions is patient education. Individuals must learn what substances to avoid and what to do during allergic attacks. Potentially life-threatening attacks can be avoided with proper education.