Urticaria (Hives)

Urticaria (hives) usually starts with a red, itchy patch of skin and develops into a raised welt with clearly defined borders. It is often caused by an abnormal immune response. While it's often the result of an allergy to a food or medicine, there are non-allergic causes as well. Symptoms may come and go quickly or they can be long-lasting. 

This article explains the symptoms and possible causes of urticaria. It also covers how to treat urticaria and when to seek tests and treatment for your symptoms.

What Is Urticaria?
Verywell / Emily Roberts

Symptoms of Urticaria

Urticaria can affect people of any age and may develop on any part of the body, including the palms of the hands and soles of the feet. About 20% of people experience hives at some point in their lives.

Here's what hives look like:

  • They appear as raised welts (sometimes called wheals or weals).
  • They vary in shape and size and usually have a clearly defined border.
  • When pressed, the center will "blanch" (turn white).

In addition, hives are itchy, some more than others.

Most hives are acute (come on suddenly) and self-limited, resolving on their own within 24 to 48 hours. Others may take days or weeks before they fully go away. During this time, it is not uncommon for the hives to disappear and reappear.

If hives persist for six weeks or more, this is known as chronic hives. Chronic hives can persist for months or even years and may be triggered by stress, heat, cold, and other physical triggers.

Symptoms of hives may be confused with those of other conditions, including eczema (atopic dermatitis) and psoriasis.

Unlike with hives, symptoms of eczema include dryness, crusting, cracking, oozing, or bleeding, often on the elbows, knees, and hands, and sometimes around the eyes.

Psoriasis is an autoimmune condition that produces thick, scaly lesions on the skin.

This photo contains content that some people may find graphic or disturbing.

urticaria on legs
Hives on leg.

Causes of Urticaria

In general, all forms of urticaria are a result of an abnormal immune response. While an allergy is the most common cause, it is not the only cause.

Allergy-Induced Urticaria

Allergy-induced urticaria occurs when the immune system responds abnormally to an otherwise harmless substance. Your immune system releases a chemical known as histamine into the bloodstream. Histamine is an inflammatory substance that causes allergy symptoms, affecting the respiratory system, gastrointestinal tract, and skin.

Common triggers of allergy-induced urticaria include:

Chronic Idiopathic Urticaria

Chronic urticaria is often idiopathic (having no known cause) and may worsen in times of stress.

The exact pathway of the condition is unknown. In some patients, autoantibodies (immune proteins that target the body's own cells) are found in the blood, but these autoantibodies are not necessarily disease-causing.

Testing for these autoantibodies is generally discouraged because positive results do not diagnose chronic urticaria or help in routine treatment decisions.

While the underlying cause of chronic urticaria may be different ​from allergy-induced urticaria, the outcome will be the same (albeit longer-lasting). Women tend to be affected more than men.

Physical Triggers

Common physical triggers of hives include exposure to:

  • Heat
  • Cold
  • Sunlight
  • Pressure
  • Vibration
  • Water
  • Friction

A form of urticaria called exercise-induced urticaria can be triggered when you exercise after being exposed to an allergen, such as dust, a medication, or a specific food.

Infections and Diseases

Some infections and diseases may also produce acute or chronic hives. These include hepatitis, chronic kidney disease, lymphoma, and any number of autoimmune disorders (including lupus, Hashimoto's thyroiditis, and rheumatoid arthritis).

What Medications Can Cause Hives?

Drug-induced urticaria is the term used when hives are caused by a prescription or over-the-counter (OTC) medication. Common medications that may cause urticaria include:

How to Treat Hives

Most acute hives will go away on their own within a few days. A wet, cool compress can soothe the itching and swelling.

Treatment for hives that don't resolve naturally depends on the cause and symptoms. Some cases may take up to several weeks and require oral antihistamines to help alleviate the symptoms.

Over-the-counter antihistamines such as Allegra (fexofenadine), Claritin (loratadine), and Zyrtec (cetirizine) usually provide ample relief. Stronger antihistamine drugs may be obtained by prescription.

If antihistamines are not adequate for providing relief, other drugs may be added or substituted, particularly if the cause is non-allergic. These include:

  • H2 blockers, such as Pepcid (famotidine) and Tagamet (cimetidine), can be used in combination with antihistamines to reduce vascular swelling.
  • Corticosteroids, like Prednisone, can dampen the immune response and quickly reduce itching and swelling. While this can be useful for a few days, it is generally not recommended long-term due to the potential for significant side effects.
  • Leukotriene modifiers like Accolate (zafirlukast) and Singulair (montelukast) are commonly used to treat asthma. However, they're also used off-label to treat certain forms of chronic idiopathic urticaria that haven't improved with antihistamines alone.
  • Doxepin is a tricyclic antidepressant that also acts as a powerful antihistamine when used in low doses.
  • Xolair (omalizumab) is an injectable monoclonal antibody that is effective for treating chronic forms of urticaria that have not responded to antihistamines.

Avoiding the trigger in the first place, when possible, can prevent hives from forming altogether.

Complications and Risk Factors Associated With Hives

Urticaria may sometimes be accompanied by a deep-seated swelling of tissue known as angioedema, most commonly affecting the face, lips, tongue, throat, or eyelids.

If this happens and you are having trouble breathing, call 911 immediately.

Are There Tests to Diagnose Hives?

Urticaria can usually be diagnosed based on a review of your medical history and the characteristic appearance of the rash. Lab tests and imaging are generally not required.

The severity of an eruption can be classified based on an assessment tool called the urticaria activity score (UAS). For this, a patient rates the two primary symptoms—the wheals and the itchiness (pruritus)—on a scale of 0 (low disease activity) to 3 (severe disease activity).

Having a maximum score of 6 often means that a patient requires further treatment, particularly if the symptoms are chronic.

If further testing is needed, it may involve one of the following:

  • Allergy testing may be recommended if you’ve had a severe hypersensitive reaction to food, medications, or an insect sting. A skin test or a specific IgE test are the two most common forms of allergy testing.
  • Physical challenge tests are used to confirm that your chronic hives are physically induced. This involves the application of the suspected stimuli—such as ice, heat, vibration, light, or friction—to the skin. Exercise testing may also be used in the case of exercise-induced urticaria.
  • Skin biopsy (the removal of a tissue sample for lab evaluation) is only indicated if the hives fail to improve and no other cause can be found. Unless there is some unusual explanation for the wheals, a biopsy of a hive will usually not reveal anything abnormal.

When to See a Healthcare Provider 

You may want to contact your healthcare provider if your hives:

  • Cover a large area of your body
  • Are not resolving on their own or responding to OTC medications (i.e., antihistamines) within a few days
  • Are caused by a known allergy

In rare cases, hives may develop as part of a potentially life-threatening allergy known as anaphylaxis.

Call 911 or have someone take you to your nearest emergency room right away if your hives are accompanied by:

  • Facial swelling
  • Difficulty breathing
  • Rapid heartbeat
  • Vomiting

If left untreated, anaphylaxis can lead to shock, coma, heart or respiratory failure, and death.

Summary

Hives, or urticaria, are raised, red, itchy bumps on the skin. They are commonly caused by an allergy, but may also be caused by physical factors (such as cold or heat) or an underlying disease. Most cases of acute hives go away on their own within a day or two. Chronic cases may require antihistamines or other medications to relieve symptoms.

A Word From Verywell

While hives can be unsightly and uncomfortable, they usually aren't serious. However, if they start to interfere with your quality of life, ask your healthcare provider for a referral to an allergist who can perform tests to pinpoint the cause.

Frequently Asked Questions

  • What causes hives?

    Hives can be caused by an allergy to a food or other substance, a medication, a physical trigger (such as cold water or weather), or an underlying autoimmune disease (such as lupus or thyroid disease). In some cases, there is no known cause; this is called idiopathic urticaria.

  • What do hives look like?

    Hives appear as raised welts on the skin. They usually have a clearly defined border and can vary in shape and size. When pressed, the center will "blanch" (turn white).

  • Can stress cause hives?

    Yes, sometimes stress can cause the release of histamines that result in hives.

  • Are hives contagious?

    Hives themselves are not contagious. However, if the hives are caused by an underlying infection, the infection itself can be contagious.

  • How do I get rid of hives?

    Most of the time, acute hives go away on their own. If they don't, antihistamines and/or other medications are usually effective.

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Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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Additional Reading