Hives: Symptoms, Causes & Treatment

Hives, also called urticaria, are itchy, swollen red welts that develop when the skin reacts to a trigger. Acute hives usually last less than 6 weeks, while chronic hives continue to return or persist for more than 6 weeks.

Hives can be triggered by allergies, insect bites, medications, foods, infections, stress, or changes in temperature. Symptoms often disappear within 24 hours without leaving scars, but severe allergic reactions can also cause swelling of the lips or throat and trouble breathing.

Hives are diagnosed based on symptoms, a skin examination, and, in some cases, blood tests or allergy testing. Treatment depends on the cause and may include avoiding triggers and using medications such as antihistamines, corticosteroids, or other therapies for chronic cases.

Common symptoms

The main symptoms of urticaria (hives) are:

• Red spots of various sizes on the skin

• Pink or reddish patches on the skin

• Raised red welts

• Skin swelling

• Intense itching

These symptoms may affect one area of the skin or spread throughout the body. They usually last up to 24 hours and go away without leaving marks or scars.

However, new spots may appear on other parts of the body and continue to come back for around 6 weeks or longer. This type of hives is called chronic urticaria.

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In cases of a severe allergic reaction or anaphylaxis, symptoms may include swelling of the lips, tongue, throat, or eyes, difficulty breathing, dizziness, or fainting. If these symptoms occur, seek emergency medical care immediately.

Confirming a diagnosis

Hives are diagnosed by a dermatologist, allergist, or primary care provider based on symptoms, a skin exam, medical history, recent medication use, and contact with possible allergens.

The doctor may also order blood tests and allergy testing, which is done in the doctor's office by applying different substances to the skin to check for symptoms.

What causes hives?

The most common causes of hives include:

• Insect bites
• Allergies to clothing fabrics, pollen, latex, or sweat
• Foods such as peanuts, eggs, or shellfish
• Food colorings or preservatives
• Excess stress
• Extreme heat or cold
• Infections, such as mononucleosis
• Medications
• Cleaning products, toxic chemicals, or poisonous plants
• Medical conditions, such as lupus or leukemia

It is not always possible to determine the cause of hives, but your doctor or allergist can order blood tests or allergy testing to better understand your symptoms and determine the most appropriate treatment.

Main types

Hives can be classified as acute or chronic depending on how long the symptoms last. They may also be categorized according to their cause.

According to the American Academy of Allergy, Asthma & Immunology, acute hives can last from less than 1 day up to 6 weeks, while chronic hives persist or recur for more than 6 weeks.

1. Acute urticaria

Acute urticaria occurs after exposure to an allergen that triggers the release of histamine in the body. Symptoms usually last less than 6 weeks, although individual hives generally disappear within 24 to 72 hours.

2. Chronic urticaria

Chronic urticaria is characterized by symptoms that persist or recur for more than 6 weeks and may continue for months or even years.

3. Stress hives

Stress hives are hives that develop or worsen during periods of emotional stress or anxiety. Although stress does not directly cause hives, it can trigger outbreaks or make existing symptoms worse.

4. Cholinergic urticaria

Also known as heat-induced hives, cholinergic urticaria develops when body temperature rises due to exercise, hot showers, spicy foods, or emotional stress. Symptoms usually go away within a few hours.

5. Gestational urticaria

Gestational urticaria may be triggered by stress, food allergies, insect bites, or medications. It can also occur due to hormonal changes during pregnancy, including increased prolactin and progesterone levels.

6. Urticaria pigmentosa

Urticaria pigmentosa is caused by an increased number of mast cells in the skin. It most commonly affects infants and young children.

7. Contact urticaria

Contact urticaria develops after direct contact with substances that trigger an allergic reaction, such as latex or certain plant resins.

8. Solar urticaria

Solar urticaria is a rare type of hives triggered by exposure to sunlight. It causes an exaggerated immune response that leads to itchy, raised welts on sun-exposed areas such as the arms, hands, neck, chest, and face.

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9. Urticarial vasculitis

Urticarial vasculitis is a rare form of hives that causes inflammation of the blood vessels. In addition to hives, it can cause pain and a burning sensation in the affected areas.

Hives treatment

Treatment for hives should be guided by a dermatologist, allergist, or primary care provider and generally involves medications to relieve symptoms.

The main medications that may be prescribed include:

• Antihistamines, such as fexofenadine, loratadine, diphenhydramine, or cetirizine

• Corticosteroid creams or ointments, such as hydrocortisone or dexamethasone

• Oral corticosteroids, such as prednisone or prednisolone

• Biologic therapy, such as omalizumab

• Immunosuppressants, such as cyclosporine or tacrolimus

These urticaria medications should only be used under medical supervision and according to the severity of symptoms and the underlying cause.

According to the CDC, epinephrine is the first-line treatment for anaphylaxis and should be administered immediately. Severe cases require emergency care and may also involve antihistamines, corticosteroids, and airway support.