What are hives?
Hives are red, very itchy, swollen areas of
the skin. They arise suddenly and may leave
quickly, (in 1-2 hours), last for as long as 24
hours, or persist for months. They often
appear in clusters. New clusters may appear
as old ones fade. Doctors refer to hives as
urticaria. Swelling deeper in the skin that
may go with hives is called angioedema.
This may be seen on the mucous
membranes, lips, and eyelids. This is often a
result of an allergic reaction.
Hives is a condition that affects many
people. At some point in their lives 2 out of
10 people suffer an outbreak of hives.
What causes hives?
The cause of most of the chronic cases of
hives is unknown. Allergic and non-allergic
causes can produce hives. A reaction to
foods or drugs is sometimes the cause.
Foods that are known to cause more
problems are nuts, tomatoes, and shellfish.
Common drugs that could be causes are
penicillin, sulfa, seizure medicines, and
aspirin. In rare cases, a viral infection or
underlying disease may be the cause. Some
hives are caused by stroking of the skin or
tight fitting clothing. Sunlight or a sun lamp
can also cause hives. Blood and urine
samples may be taken to screen for rare
Will they go away?
For most patients, hives will disappear as
mysteriously as they appeared. Sometimes
they fade within hours, only to return later.
At times, hives may last for months. If
needed, your doctor can prescribe
antihistamines. These are medicines that
relieve itching and cause the hives to fade
ξ Do not eat any food or medicine that
causes you to have hives.
ξ Stay away from other causes that may
produce hives, such as animals. Do not
take hot baths or showers when your
hives flare up. The heat will cause
further redness and itching.
ξ Some people get hives only after taking
a hot shower or after getting hot and
sweaty from exercise. Let your doctor
know if you have this problem.
Others get hives when they are exposed to
cold temperatures. Again, tell your doctor if
you have this problem. If you do, don’t dive
directly into a pool or lake. Take time to
adjust to the water’s temperature before
diving into it.
ξ If you have hives which happen often or
last for a long time, your doctor may
give you antihistamines to take routinely.
Avoid the cause of the hives if it is known.
Antihistamines may be prescribed. Some
medicines that do not make people sleepy
are Claritin (loratadine) and Allegra
(fexofenadine). Antihistamines such as
Zyrtec (cetrizine), Atarax (hydroxyzine),
and Benadryl (diphenhydramine), also treat
the itching and allow hives to fade. Other
medicines may be prescribed. Your doctor
will discuss the options with you.
Call your Doctor Right Away If You
Have Hives and You
ξ Have trouble breathing or
ξ Feel dizzy or shaky.
ξ Have stomach pain or cramps or
Your health care team may have given you this information as part of your care. If so, please use it and call if you
have any questions. If this information was not given to you as part of your care, please check with your doctor. This
is not medical advice. This is not to be used for diagnosis or treatment of any medical condition. Because each
person’s health needs are different, you should talk with your doctor or others on your health care team when using
this information. If you have an emergency, please call 911. Copyright © 8/2016. University of Wisconsin Hospitals
and Clinics Authority. All rights reserved. Produced by the Department of Nursing HF#4202.