Urticaria (Hives)

Overview

Urticaria, commonly known as hives, is an itchy skin rash made up of raised welts, called wheals, that can be pale or red and surrounded by a flush. A hallmark of hives is that individual welts come and go quickly, often within hours, and can change shape and move to new areas. They can be a few small spots or cover large parts of the body.

Hives happen when cells in the skin release histamine and other chemicals, making small blood vessels leak and the skin swell. Most cases are short-lived (acute) and triggered by an allergy, infection, or other stimulus, settling within days to a few weeks. Some people have long-lasting (chronic) hives. While usually harmless, hives that come with deeper swelling of the lips, tongue, or throat, or with breathing difficulty, can signal a serious allergic reaction needing emergency care.

Common Causes

Hives have many possible triggers, and the cause is not always found. Common ones include:

• Allergic reactions: foods, medications, insect stings, or latex. See food allergy.
• Infections: viral illnesses, common especially in children.
• Physical triggers: heat, cold, pressure, sunlight, exercise, or sweating.
• Stress: emotional stress can provoke or worsen hives.
• Medications: including some antibiotics and pain relievers.
• Chronic urticaria: long-lasting hives, sometimes linked to immune factors, often with no clear trigger.

Hives can occur with deeper swelling called angioedema and, in severe allergic reactions, with anaphylaxis.

Associated Symptoms

Hives may appear alone or with other symptoms:

• Intense itching of the skin
• Raised welts that blanch (whiten) when pressed and fade within hours
• Redness or a burning, stinging feeling
• Deeper swelling of the lips, eyelids, or face (angioedema)
• In allergic reactions, difficulty breathing, wheezing, or dizziness
• Symptoms of an underlying infection in some cases

Hives with swelling of the tongue or throat, trouble breathing, or fainting suggest a severe allergic reaction and need emergency care.

Diagnosis & Evaluation

Hives are usually diagnosed from their appearance and pattern. Evaluation may include:

• History: recent foods, medications, infections, and physical triggers, and how long episodes last.
• Examination: confirming the welts blanch and individual lesions fade within a day.
• Trigger review: identifying allergic or physical triggers where possible.
• Tests for chronic hives: blood tests or specialist referral when hives last more than six weeks.
• Allergy testing: if a specific allergen is suspected.

Treatment & Management

Most hives respond well to antihistamines and avoiding triggers:

• Antihistamines: non-drowsy oral antihistamines are the first-line treatment and can be taken regularly for ongoing hives.
• Avoiding triggers: steering clear of identified foods, medications, or physical triggers.
• Cool comfort: cool compresses, loose clothing, and avoiding heat and scratching to ease itching.
• Short courses of steroids: sometimes used for severe flares under medical guidance.
• Specialist treatment: additional therapies for chronic hives that do not respond to antihistamines.
• Emergency treatment: epinephrine for hives that are part of a severe allergic reaction.

Self-Care & Prevention

You can reduce hive flare-ups by identifying and avoiding what sets them off:

• Keep a diary of foods, activities, and exposures to help spot triggers.
• Avoid known food, medication, or insect-sting triggers once identified.
• Stay cool, wear loose, soft clothing, and avoid overheating, hot showers, and tight pressure on the skin if these trigger you.
• Manage stress, which can provoke or worsen hives.
• Take antihistamines regularly if your doctor recommends them for ongoing hives, rather than only after welts appear.
• Protect your skin from extreme cold or sun if these are triggers.

For severe reactions, carry any prescribed epinephrine auto-injector. If hives keep returning for more than six weeks, see a doctor for evaluation and a longer-term plan.

When to See a Doctor

See a doctor if hives are severe, keep coming back, last more than a few weeks, or do not respond to antihistamines. Call emergency services immediately if hives come with:

• Swelling of the tongue, throat, lips, or face
• Difficulty breathing, wheezing, or tightness in the throat
• Dizziness, fainting, or a fast, weak pulse
• Hives spreading rapidly after a food, medication, or insect sting

These signs suggest anaphylaxis. Use a prescribed epinephrine auto-injector right away and seek emergency care.

Related Topics

Frequently Asked Questions

References

1. American Academy of Allergy, Asthma & Immunology (AAAAI). Hives (Urticaria).
2. Mayo Clinic. Chronic hives — Symptoms and causes.
3. American Academy of Dermatology (AAD). Hives.
4. MedlinePlus, U.S. National Library of Medicine. Hives.