Ask the Allergist: Pinpointing the Cause of Hives

Q: I’ve broken out in hives four times in the past year and can’t pinpoint what may be causing it. What should I do?

Chitra Dinakar, MD: 

Hives can be scary. When you get these red, itchy welts on your skin, you may worry you’ve had an allergic reaction to an allergen, such as a food allergen, or maybe you’re reacting to an insect sting, or something that contains latex. What if you’re not able to identify the trigger? Don’t worry – 1 in 3 people develop hives at some point in their life.

There are two types of hives: acute and chronic.

When hives are acute, that means you get symptoms for a short period of time. Perhaps it’s the first time you ate peanut butter and you developed hives. Or a bee stings you and its venom causes hives. Acute hives are usually immediate reactions and typically last for a few hours to days.

When it’s chronic hives, or hives that occur over a longer period of time such as a few weeks, allergists think of it as an “over-excitement” of the immune system. In other words, your immune system is reacting appropriately – it is fighting a trigger such as a virus, for example – but then it gets a bit “excited” in the process and starts attacking the allergy cells in your skin. When the immune system calms down, your symptoms will get better. Hives alone are not life-threatening.

Allergists will ask a lot of questions to explore possible triggers. Have you eaten a new food or started a new medication? Have there been any changes in your diet? Have you lost weight? Is there anything upsetting your body system that suggests an autoimmune disease. Has there been a recent infection? The history of symptoms is very important in determining what is triggering the hives.

If there is no obvious trigger or the trigger is unknown, then allergists will consider therapies to calm down the immune system and to reduce the itchiness and swelling so that you feel better. Typically allergists recommend antihistamines such as the ones used to treat seasonal allergies. We might also recommend H2 blockers to help calm symptoms. And if those don’t work, then there are other therapies, including a new biologic medication that can be tried.

The important thing to remember is that hives alone are not life-threatening. Nothing horrible is happening inside your body. The immune system just needs to reset itself. One way of thinking of it is – ‘This too shall pass.’

Chitra Dinakar, MD, FACAAI, is a board-certified allergist and immunologist and a professor with the Sean N. Parker Center for Allergy & Asthma Research at Stanford University.

Have a medical question? Email or write to Ask the Allergist, Allergy & Asthma Network, 8229 Boone Blvd., Suite 260, Vienna, VA 22182.


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