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Hives or Urticaria: Allergy Clinic (7325)

Hives or Urticaria: Allergy Clinic (7325) - Clinical Hub, Patient Education, Health and Nutrition Facts For You, Respiratory


Hives or Urticaria: Allergy Clinic

Why do people get hives?

About 20 percent of people will have hives sometime during their lives. Hives lasting
longer than 6 weeks are called “chronic urticaria”. Most of the time the cause of chronic
urticaria is unknown.

What causes hives and how are they diagnosed?

Hives or urticaria is swelling of the skin caused by the release of chemicals, such as
histamine, from mast cells. Hives happen in response to a range of triggers including:
ξ Non-allergic:
o Post-viral
o Physical (heat, cold, touch, exercise, vibration, sun exposure)
o Certain health conditions (e.g. thyroid disease)
o Stress
ξ Allergic:
o Foods
o Medicines
o Insect stings
o Contact allergy (such as pets or grass)

Hives are raised, swollen welts which are very itchy and vary in size. They can appear on
certain parts of the body or cover the whole body. They do not stay in the same place and
may appear in other places, changing shape and size. They can last for 2-4 hours or keep
occurring over several weeks.

Hives are diagnosed based on medical history and physical exam. Families often label
rashes as "hives" even though the rash does not appear hive-like. Because hives tend to
change quickly, it is helpful to take a picture of the hives and bring it to the doctor’s

Evaluation of hives during a clinic visit may include blood tests or other testing of
possible causes.

How are hives treated?

Avoidance is the best treatment for hives though this is not always possible especially
with non-allergic hives. Antihistamines are the preferred treatment for hives.

Non-sedating antihistamines (such as loratadine or cetirizine) may be used daily
especially with non-allergic urticarias.

With chronic urticaria (hives lasting greater more than 6 weeks), other medicines may be
added when needed. These may include:
ξ Doubling of non-sedating antihistamines (morning and evening doses)
ξ H-2 antagonists (such as ranitidine or Zantac®)
ξ Leukotriene modifier (such as Singulair®)

Others may be added for hives that do not respond to the above medicines.

Planning and Care

Finding out the cause of hives is not always easy and in some cases, the cause of hives
may not be found.

It is helpful to have an up-to-date history of exposures:

ξ Do you or your child have food allergies? Did you or your child have a food
allergy exposure? If so, follow the food allergy action plan.
ξ Were you or your child exposed to cold air, heat or the sun (physical urticaria)?
ξ Were you or your child stung by a bee while outdoors?
ξ Did you or your child get a new medicine at home or a nonsteroidal anti-
inflammatory medicine (like ibuprofen)?
ξ Are you or your child getting over an illness?

If there is an outbreak of hives, take an antihistamine and call the doctor’s office. If there
are breathing problems, call 911, and give epinephrine if you have it.

The best way to manage hives is by staying away from the foods, medicines, stinging
insects, or other allergens that cause you or your child’s hives.

For more information about hives you may visit this website:

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.
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