Published on December 12, 2019 at 8:00 / Updated on April 16, 2020 at 16:31

Hives, also known as urticaria, are a very common, noncontagious health problem. They are a skin reaction characterized by swollen, itchy red bumps or plaques.

Hives appear without warning and usually go away after a few hours. However, they may reappear elsewhere on the body. In some cases, the bumps will spread and join together, forming larger lesions known as plaques.

Hives are sometimes accompanied by a similar condition called angioedema, which affects deeper layers of the skin.

Angioedema has the following symptoms:

  • Swelling of the face, eyelids, ears, mouth, throat, tongue, airways, hands, feet, and genitals
  • Itchy, uncomfortable swelling
  • Slightly red or normal-looking skin

Causes and triggers

Hives are sometimes an allergic reaction, but they more often have a different trigger. They are generally categorized into one of three types depending on the cause.

Acute hives

Acute hives last anywhere from a few days to 1 or 2 weeks. Potential triggers include the following:

  • An infection due to a virus, bacteria, or parasite
  • Medications such as antibiotics or nonsteroidal anti-inflammatory drugs (e.g., aspirin, ibuprofen)
  • A bug bite
  • A food allergy
  • Contact with latex or certain chemicals or plants
  • Physical stress (e.g., exposure to light or heat) or emotional stress
  • A health problem or autoimmune disease

It is not always possible to determine the cause of acute hives.

Chronic hives

Hives are said to be chronic if they last for more than 6 weeks. The condition is rarely permanent, and its symptoms vary widely. Individuals may experience episodes for months or even years, followed by periods of remission. The cause of chronic hives is often unknown. In some cases, they are linked to an autoimmune disease.

Inducible hives

A form of chronic hives, inducible hives have physical triggers that include the following:

  • Exposure to the cold
  • Perspiration or change in body temperature
  • Vibrations (especially when driving)
  • Pressure
  • Physical exercise
  • Water or daylight (rare)


There are two parts to treating hives: avoiding triggers and taking medication to alleviate symptoms.

The following measures are recommended to relieve itching:

  • Take a cold bath or shower
  • Do not scratch the affected area
  • Wear loose-fitting clothing
  • Take antihistamines (e.g., Claritin)

Prescription medication may be used in certain cases. It may be necessary to administer epinephrine (EpiPen) if the reaction is severe or hampers breathing.

When should I see a health care professional?

Hives can sometimes develop into a more serious condition. If you experience any of the following symptoms, consult your health care provider immediately:

  • Signs of angioedema
  • Wheezing or difficulty breathing
  • Constriction of the throat
  • Stomach pains
  • Weakness or any other body-wide symptom
  • Fever or chills
  • Deeply coloured hives
  • Dizziness or fainting spells
  • Nausea or vomiting
  • Hives that spread all over the body after an insect bite (sign of a severe allergic reaction)

It's also recommended to see a health care professional if your symptoms last more than two days.

For more information:
Allergy Asthma and Immunology Society Of Ontario

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