Version July 2025
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What are hives? —
These are patches of skin that are usually very itchy (picture 1 and picture 2 and picture 3). The patches look puffy or raised compared with 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 (picture 4).
Hives can happen because of an allergy or when the body's immune system is "activated" for another reason. In most cases, hives come and go within a few hours. But they can show up again and again in some people.
Some people who get hives also get a condition called "angioedema." This is puffiness or swelling (figure 1). It usually happens in the face, eyelids, ears, mouth, hands, feet, or genitals (picture 5).
Why did I get hives? —
If you just got hives for the first time, you might have a new allergy to something. People can get hives because of allergies to:
●Medicines, such as antibiotics or aspirin
●Foods, such as eggs, nuts, fish, or shellfish
●Something they touched, such as a plant, animal saliva, or latex
●Insect stings
If your hives are caused by an allergy, you need to avoid whatever you are allergic to.
Hives can also be caused, or "triggered," by infections, such as with a virus or bacteria. In this case, the hives happen because your immune system was activated to fight the infection. Hives can appear days or weeks after an infection. You might remember being sick recently. But hives can also happen with mild infections you might not have noticed. Hives of this type usually only last a few days.
There are also "physical" triggers for hives, such as:
●Cold air, water, or sun on the skin
●Exercise
●Something pressing or vibrating against the skin
●Changes in body temperature (such as when you cool down after a hot shower or a work out)
It is often not possible to tell what triggered hives.
What are chronic hives? —
"Chronic" means long term. If you have had hives on most days for more than 6 weeks, you might have chronic hives. These are not caused by an allergy. In most cases, doctors do not know what causes chronic hives.
If you have chronic hives, you probably need to take medicines every day to control them. Luckily, chronic hives usually go away with time.
How are hives treated? —
You might not need treatment. Hives usually go away on their own in a few days or weeks.
If you have hives for the first time, talk to your doctor or nurse about whether you need treatment. If you do, the first step is to figure out if anything triggered the hives. If so, you need to avoid that trigger.
To relieve itching, you can take medicines called "antihistamines." These are the same medicines people usually take for allergies.
If you have severe hives or your hives do not go away, your doctor or nurse might suggest you take "steroid" medicines for a short time. These work well to relieve itching and reduce swelling. But you should not take them for long, because they can cause serious side effects.
When should I get medical help? —
Call for emergency help right away (in the US and Canada, call 9-1-1) if you suddenly get hives or swelling and also have any of these symptoms:
●Trouble breathing, hoarse voice, or wheezing (hearing a whistling sound when you breathe)
●Swelling, especially in the mouth or throat
●Throat tightness
●Feeling dizzy, or almost fainting
Patient education: Inducible hives (The Basics)
Patient education: Chronic hives (The Basics)
Patient education: Anaphylaxis (The Basics)
Patient education: Itchy skin (The Basics)
