Hives (technically called “urticaria”) are generally harmless but itchy and uncomfortable welts on the skin forming a rash. Hives are a skin irritation caused by histamine released into the bloodstream. The histamine release is triggered most often by an allergen, such as peanuts, pet dander, or pollen, but can also come about from such disparate causes as heat, abrasive clothing, diseases such as lupus, or a blood transfusion.
Hives display as circular, swollen red or sometimes white welts on the skin. The welts can be anywhere from a few millimeters to several centimeters in diameter. They occur most often on the neck, trunk, arms, and legs. The welts generally arise suddenly, as a batch forming a rash. The individuals welts may resolve quite quickly as others form, giving the appearance that the rash is moving, and changing in size and shape.
The rash typically lasts about 24 hours, but it can be less or much more. Anything less than six weeks is classified as “acute hives,” while anything longer than six weeks is classified as “chronic hives.”
In addition to the visual symptoms, hives are also marked by an itching, which can be mild to severe. Sometimes, though only rarely, there is a burning or stinging sensation on the skin as well.
Note that when more severe symptoms are present, including when the swelling is on the inside as well, including in the throat and mouth, adversely affecting breathing, this is an indication that one is not having a simple hives reaction, but possibly a condition called angioedema. Unlike hives, angioedema can be quite serious and in extreme cases even life threatening, and so requires immediate medical attention.
Diagnosing hives means more than just ascertaining that one has the hives rash. It also means attempting to identify the cause. It’s important to know what triggers an outbreak of hives, because this will tell the person what they need to avoid in order to keep the hives from persisting or getting worse, and in order to prevent future outbreaks.
Often people already know to what they are allergic, as they have suffered from hives or other allergic reactions in the past and identified the trigger. But it is also common that they do not yet know. (And may never know; even with investigation in a significant number of cases of hives-including about 80% of the cases of chronic hives-the cause is not discovered.) There are many things that a person and their doctor can do to seek the trigger for hives.
A person who is prone to hives should keep a journal describing each outbreak, including precisely when it started and when it went away. They should also then make note of any overlapping suspicious events, such as the presence of an animal they had not been around before, and a higher than usual pollen count in the air. They should note any foods they ate during that period that are common allergens, such as eggs, peanuts, or shellfish, as well as any and all medications, vitamins, supplements and herbs they took, including dosage. Also, they should write down if the hives were correlated with any general change of health, such as a fever, loss of energy, or loss of weight.
A doctor can also perform an allergy skin test. Generally this involves placing tiny drops of purified allergen extracts of various substances onto the skin that has been lightly punctured or pricked. If the results of this test are ambiguous or unsatisfactory, a doctor may use an intradermal test, where the tiny amounts of allergan extract are injected deeper into the skin.
In addition to seeking to identify what is triggering the hives so that it can be avoided, a doctor may recommend an antihistamine-prescription or over the counter-as well as cool compresses or a cool bath to help relieve the itching.
“Allergies and Hives (Urticaria and Angioedema).” WebMD.
“Hives and Angioedema.” Mayo Clinic.
“Understanding The Hives.” Allergy Escape.