Health education · SkinSkin health
Hives (urticaria): understanding welts, relieving itch and recognizing an emergency
Swollen welts appear suddenly, itch, then fade before coming back elsewhere? It may be hives, a common skin reaction: about 1 in 5 people will have an episode during their lifetime.5
Hives can come with an infection, an allergy or certain physical triggers, but up to half of cases have no known cause.1
Trouble breathing, a tight throat, a swelling tongue or feeling very unwell need immediate help: call 9-1-1.2,6
Because new welts can appear while others fade, the rash can seem continuous even though each welt is short-lived.3
Types
Acute or chronic hives: what’s the difference?
| Type | What it means |
|---|---|
| Acute hives | Usually lasts six weeks or less.1 |
| Chronic hives | Lasts more than six weeks, sometimes months or years. It is more common in adults and in women.1 |
| Chronic spontaneous urticaria | Episodes occur without a specific outside trigger; an immune system dysfunction, often autoimmune, is involved.1,5 |
| Inducible urticaria | Episodes are caused by a specific stimulus: cold, heat, pressure on the skin, vibration, light, sweating or exercise.1,5 |
The six-week threshold refers to how long episodes keep coming back, not how long a single welt lasts.1,3
Causes
What are the possible causes?
An infection
In children, the most common cause is an immune reaction to an infection, usually a virus.3
Welts that appear during an illness therefore don’t automatically mean a food or medication is to blame.
An allergy
A food (nuts, eggs, shellfish), a medication (antibiotics, aspirin, ibuprofen), an insect sting, latex, pet dander or pollen can cause acute hives.1
What was eaten or taken, how long before the welts appeared and other symptoms help guide the assessment.
Angioedema
What is angioedema?
Angioedema is deeper swelling under the skin. It can affect the face, lips or throat, with or without hives.1,5
A possible emergency
Swelling of the face or lips needs prompt assessment. Difficulty swallowing or breathing is an emergency: call 9-1-1.1
Ask your pharmacist for advice before taking an over-the-counter medication.2
Treatments
Which treatments can help?
Antihistamines
Oral antihistamines are the main treatment.1 Newer-generation, low- or non-sedating ones are recommended first: older ones, such as diphenhydramine (Benadryl), more often cause drowsiness.1,4
In chronic hives, higher doses are often needed.1 Don’t increase doses yourself or combine several products without advice.
Oral cortisone
Oral corticosteroids, such as prednisone, may be used for severe hives when other treatments aren’t enough.1
They aren’t suitable for long-term use.1
Specialized treatments
When chronic hives persist despite antihistamines, omalizumab, a biologic medication, is safe and effective in teens and adults.1
Other medications are reserved for severe cases. A referral to allergy or dermatology may be indicated.
Tests
Do you need allergy tests?
Not routinely. Diagnosis is based on symptoms, history and a skin exam. Blood tests or a biopsy may be used in some cases, and a skin test if an allergy is suspected.1
Allergy tests are only useful if an allergy is causing the hives.3
Since welts may be gone by the time of your appointment, dated photos are helpful. Also note how long a welt lasts, medications taken and the circumstances of episodes.
Seeking care
When should you see a professional?
Hives that go away on their own and don’t come back generally don’t need a visit.1 Still, you don’t have to wait six weeks to ask for help.
See a professional if:2
- there is fever, or joint pain and swelling;
- welts cover a large part of the body;
- they come and go for no reason, or last more than 7 days;
- a recently started medication could be the cause;
- itching doesn’t decrease despite an antihistamine after 24 hours in a child aged 2 to 11, or after 48 hours from age 12.
In Quebec, Info-Santé 811, option 1, lets you speak with a nurse at any time.2
Emergency
When to call 9-1-1?
Hives or swelling of the face, lips or tongue can be part of a severe allergic reaction (anaphylaxis).2
Call 9-1-1 if any of these signs are present:2,6
- a high-pitched sound when breathing or difficulty breathing;
- bluish lips or fingers;
- feeling weak, dizzy or fainting;
- a very fast heartbeat;
- abdominal pain, vomiting or diarrhea.
If anaphylaxis is suspected, give epinephrine immediately, if available, then call 9-1-1. If symptoms don’t improve, a second dose can be given as soon as 5 minutes after the first.6
Epinephrine is the only medication that treats anaphylaxis: an antihistamine doesn’t replace it. Go to the hospital, ideally by ambulance, even if symptoms improve, because the reaction can come back.6
When to consult at the Clinique IPS du Palais?
A nurse practitioner can assess hives that keep coming back or persist, look for a trigger, adjust antihistamine treatment and refer you to an allergist or dermatologist when indicated.
If you have trouble breathing, a swelling tongue or feel faint, call 9-1-1.
Sources
- Canadian Dermatology Association. L’urticaire (French page). Modified January 30, 2026, accessed October 30, 2026. dermatologue.ca
- Santé Québec. Urticaire (plaques rouges) (in French). Updated January 1, 2026, accessed October 30, 2026. sante.quebec
- The Royal Children’s Hospital Melbourne. Hives (urticaria). Reviewed June 2026, accessed October 30, 2026. rch.org.au
- Fein MN, Fischer DA, O’Keefe AW, Sussman GL. CSACI position statement: Newer generation H1-antihistamines are safer than first-generation H1-antihistamines and should be the first-line antihistamines for the treatment of allergic rhinitis and urticaria. Allergy Asthma Clin Immunol. 2019;15:61. link.springer.com
- Zuberbier T, et al. The International EAACI/GA²LEN/EuroGuiDerm/APAAACI Guideline for the Definition, Classification, Diagnosis and Management of Urticaria. Allergy. 2026;81(8):2582-2632. Abstract accessed October 30, 2026. doi.org
- Food Allergy Canada. Traiter une réaction (French page). Update date not stated, accessed October 30, 2026. allergiesalimentairescanada.ca
This sheet provides general information and does not replace an assessment or a personalized treatment plan. Published October 30, 2026.