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What are inducible hives? — Hives are patches of skin that are usually very itchy (picture 1). The patches look puffy or raised compared to the rest of the skin. Hives might look reddish in color on light-colored skin. The color changes can be hard to see on darker skin. The medical term for hives is "urticaria."
Inducible hives are hives that form in response to some sort of physical stimulation, such as heat, cold, or pressure. They are also called "physical" hives.
The most common causes of inducible hives include:
●Scraping or stroking – People who get this type of hives develop raised lines on their skin along areas that have been scraped or stroked. Doctors call this "dermatographism." If you get this type of hives, your skin might get a hive pattern that matches your fingernails after you scratch an itch.
●Cold – People who are sensitive to cold get hives when their skin starts to warm up again after being cold.
●Increased body temperature or sweating – People who are sensitive to heat or sweat get lots of tiny hives, often when they cool off after a hot shower or cool down after exercising hard.
●Vibration – People who are sensitive to vibration get hives on parts of their body that have been touching something that vibrates. If you get this type of hives, you might get them on your palms after you have been driving and holding onto a steering wheel, or after mowing the lawn.
●Pressure – People who are sensitive to pressure can get swelling anywhere on their body that has been pressed on. The swelling can start hours after the pressure. For example, if you have this problem, you might get a swollen palm a few hours after carrying a heavy bag by the handles. Or you might also get swelling of the soles of the feet after walking a long way.
●Exercise – Hives that show up during exercise can be a sign of a dangerous problem called exercise-induced anaphylaxis. If the hives show up after exercise, when cooling down, they are more likely to be the type triggered by changes in body temperature or sweating.
●Sunlight or water – Hives caused by sunlight or water are rare.
Inducible hives tend to go away and come back over a period of years. They are considered a type of chronic (or long-lasting) hives.
Should I see a doctor or nurse? — See a doctor or nurse if you aren't sure what is causing your hives or you aren't sure how to avoid the thing that triggers them.
You should also see a doctor if you have ever had symptoms of a dangerous allergic reaction called "anaphylaxis." Symptoms of anaphylaxis include:
●Trouble breathing, sounding hoarse, wheezing (hearing a whistling sound when you breathe)
●Swelling, especially around the face, eyelids, ears, mouth, hands, or feet
●Belly cramps, nausea, vomiting, or diarrhea
●Feeling dizzy or passing out
Anaphylaxis can happen with certain kinds of inducible hives. For example, if you have cold-induced hives, you could go into anaphylaxis if you go swimming in very cold water. Another example is exercise-induced anaphylaxis. If you have exercise-induced hives, it is important to stop and rest immediately if you develop hives. Continuing to exercise can be very dangerous.
Will I need tests? — Maybe. Your doctor or nurse will probably try to recreate the conditions that give you hives. For example, if you normally get hives in places where you are scratched, the doctor or nurse might gently scratch your skin. That way, they can study your skin's response.
How are inducible hives treated? — The most important part of treatment is to try to avoid whatever triggers the hives. There are also medicines called antihistamines that can reduce the itching and swelling caused by hives. Some examples of these medicines include:
●Cetirizine (brand name: Zyrtec)
●Loratadine (sample brand names: Alavert, Claritin)
●Fexofenadine (brand name: Allegra)
Patient education: Chronic hives (The Basics)
Patient education: Hives (The Basics)
Patient education: Anaphylaxis (The Basics)
