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Hives (Urticaria)

Urticaria (aka hives) are itchy, red, raised bumps on the skin, with a pale centre resembling mosquito bites.  They can vary in size from 1-2 mm to large plaques.  Typically, the individual hives come on quickly, last for less than a day, and often no more than 2-4 hours.


Urticaria can be accompanied by angioedema, which is swelling in the deeper tissues.  The swelling often affects areas with loose tissue such as around the eyes, lips, tongue, throat, hands, and feet.


Episodes of hives that last hours to days are classified as acute

Episodes that last longer than six weeks are classified as chronic.

Although most patients are concerned that hives are caused by an allergy, this is only one of many causes.

Scroll down to learn more about the different causes of hives.

Acute Urticaria

Acute urticaria can be caused by either allergic or nonallergic triggers.

Some studies have shown that up to 4/5 cases of acute urticaria are associated with infections.*

This is especially true in children but is seen in adults as well.

Allergic Triggers:



Insect stings

Contact (e.g. pet saliva, grass, etc.)

Nonallergic Triggers:


(Viral and Bacterial)

Unknown (Idiopathic)


Chronic Urticaria

Hives that last longer than 6 weeks are rarely due to an allergy. Chronic urticaria is broadly divided into two categories: 

Chronic Spontaneous Urticaria

Chronic Inducible Urticaria

This is the most common cause of hives lasting longer than 6 weeks.


This is not due to an allergy.

Instead, it is caused by a protein that your body has made (called an antibody), which activates the cells that release histamine (mast cells).

This occurs when hives develop only with a specific trigger including:

  • Cold

  • Pressure/Scratching

  • Heat/Exercise

  • Vibration

  • Sun Exposure

  • Water (rare)

What is the treatment for hives?

Asthma Treatment

Regardless of the cause or the type, hives eventually resolve over time. Chronic inducible urticaria and urticaria associated with angioedema (swelling) tend to last longer. This is not usually a life threatening condition, but has a significant impact on quality of life.

Even chronic spontaneous urticaria can be worsened by certain triggers, which should be avoided if possible.

This includes: heat/exercise, tight clothing/pressure, alcohol, stress, illness, NSAIDs (Aspirin/Advil).

Besides avoiding triggers, your allergist may suggest medications to treat your symptoms.


Non-sedating antihistamines are the mainstay of treatment for urticaria. These can be purchased over-the-counter from your pharmacy or prescribed by your physician.


Prescription options that are approved specifically for hives are Blexten (bilastine) and Rupall (rupatadine).


These can be used on a daily basis, and are often needed at higher doses than for usual allergies. The appropriate dosing should be discussed with your allergist.

Resistant Hives

Your allergist may suggest an injectable medication that specifically targets the inflammatory molecules involved in urticaria.

This medication falls under the class of treatments called Biologics.

Currently, Omalizumab (Xolair) is a biologic medication that is approved for use in Canada for the treatment of resistant urticaria.

Other Medications

Some patients may not have full control or be able to tolerate antihistamines.


They may require additional medications including Singulair (montelukast) or certain medications used in other autoimmune diseases.


Your allergist will discuss these options if they are appropriate for your condition.

Do I need an EpiPen?

The vast majority of patients with urticaria do not require an epinephrine autoinjector (EpiPen) as this is not usually a life threatening condition.

However, patients with cold urticaria, associated angioedema, or triggers that could lead to anaphylaxis may be required to carry one. Your allergist will discuss with you whether this is appropriate for your specific case.


Illustrations used with permission. Provided courtesy of EBME inc.

*Plumb et al. Arch Dermatol. 1998;134(3):319. 

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