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Overview

What Are Hives?

Hives are a temporary skin reaction that causes raised, itchy welts, also called urticaria. Individual welts can change shape, fade, and reappear in different places over a short time. Hives can affect people of any age and are usually not contagious. The rash may be uncomfortable, but most episodes do not cause lasting skin damage.

Symptoms

Symptoms of Hives

  • Raised, itchy welts (urticaria) appear on the surface of the skin.
  • Itching can range from mild to intense in the affected areas.
  • Welts can change size or shape over time.
  • Welts may fade in one area and appear in another.
  • Swelling beneath the skin (angioedema) may occur, especially around the lips, eyelids, hands, or feet.

Hives may appear on the face, lips, hands, trunk, or other body areas. Deeper swelling, known as angioedema, can accompany the surface rash and may affect the lips, eyelids, hands, or feet. Photographs can help show the appearance, but a clinician may need to assess changing or unusual rashes to confirm the diagnosis.

Causes

What Causes Hives?

Hives develop when mast cells in the skin release histamine and other chemicals. These chemicals temporarily increase leakage from small blood vessels, causing fluid to collect in the skin and form raised, itchy welts. Causes and triggers vary, and sometimes no clear trigger can be found.

  • Foods and food additives, including a food that causes an allergic reaction, can trigger hives.
  • Medicines, including some antibiotics, pain relievers, and other drugs, may cause hives in some people.
  • Infections, including viral or bacterial illnesses, can trigger hives.
  • Insect stings may cause a localized or widespread hive reaction.
  • Heat, cold, pressure, or exercise can cause physical hives in susceptible people.
  • Contact exposures such as latex or certain plants, chemicals, or personal-care products may trigger hives.
  • Chronic spontaneous hives occur when welts continue or recur without an identifiable trigger.

Risk Factors

Risk Factors for Hives

  • A personal or family history of hives or allergies may increase the likelihood of developing them.
  • Autoimmune conditions are associated with a higher risk of recurrent or chronic hives.
  • A recent viral or bacterial infection may make hives more likely temporarily.
  • Exposure to a known food, medicine, or contact trigger can provoke another episode and may be avoidable with professional guidance.
  • Heat, cold, pressure, friction, or exercise can trigger hives in people with physical sensitivities.
  • Some medicines can provoke hives and should be reviewed with a clinician rather than stopped without advice.

Complications

Complications of Hives

Most hives resolve without leaving scars or lasting skin damage. Deeper swelling, or angioedema, can affect the lips, eyelids, tongue, or throat. Rarely, hives occur as part of a severe allergic reaction that affects breathing or circulation.

Get emergency help

Know the warning signs

Seek emergency care immediately for trouble breathing, swelling of the throat or tongue, fainting, confusion, or rapidly worsening symptoms. Ordinary hives alone are usually not life-threatening, but these symptoms can signal a serious allergic reaction.

Diagnosis

How Hives Are Diagnosed

Clinicians usually diagnose hives by examining the skin and asking when the welts started, how long they last, and whether they move or change. They may ask about recent foods, medicines, infections, insect stings, contact exposures, heat, cold, pressure, exercise, and other symptoms. Testing is not always needed for a typical short-lived rash, but targeted evaluation can help when symptoms persist, recur, look unusual, or occur with whole-body symptoms.

  • A symptom and exposure history helps identify timing, possible triggers, and associated symptoms.
  • A skin examination helps distinguish hives from other rashes and assess any deeper swelling.
  • Allergy testing may be recommended when a specific food, medicine, sting, or contact trigger is suspected.
  • Blood or other testing may be considered when hives are persistent, recurrent, atypical, or accompanied by systemic symptoms.

Treatment & Management

Hives Treatment and Management

Treatment for persistent or severe hives

When hives continue or frequently return, a clinician may adjust the antihistamine dose or recommend additional treatment. A specialist may offer other options when standard antihistamines are not enough, particularly for chronic hives. Corticosteroids or other medicines may be used selectively for severe episodes, and the safest choice depends on age, pregnancy status, other health conditions, and current medicines. Medical guidance is important before changing treatment.

Prevention

Can Hives Be Prevented?

  • Record foods, medicines, illnesses, activities, and exposures before each flare to help identify what triggers hives.
  • Avoid a confirmed trigger and discuss a suspected medicine reaction with a clinician before making changes.
  • Protect the skin from extreme heat, cold, pressure, and friction when these provoke symptoms.
  • Follow the treatment plan provided by a clinician for recurrent or chronic hives.

Hives themselves are not contagious, so they cannot be spread to other people. Prevention is not always possible when no trigger can be identified, as with many cases of chronic spontaneous hives. A trigger diary and medical review may still help reduce future episodes.

Outlook and Prognosis

Outlook and Prognosis for Hives

Acute hives often improve within hours to days, although the timing varies from person to person. Chronic hives recur for six weeks or longer and may require ongoing management rather than a single treatment course. Many people can control symptoms with trigger strategies and medical treatment, but unexplained episodes may continue or return.

When Should You See a Doctor

When Should You See a Doctor for Hives?

  • Seek medical advice when hives last several days or keep returning.
  • Contact a clinician when a new medicine, food, or other exposure may be responsible.
  • Arrange prompt evaluation for marked swelling or hives with fever or other illness symptoms.
  • Ask for care when the rash is difficult to distinguish from another skin condition.

Call emergency services

Act quickly for severe symptoms

Call emergency services for trouble breathing, throat or tongue swelling, fainting, severe dizziness, confusion, or rapidly worsening symptoms. These signs may indicate a serious allergic reaction requiring immediate treatment.

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