Hives (Urticaria)

Frequently Asked Questions

ASCIA PC Hives urticaria 2024125.1 KB

Q 1: What are hives?

Hives, the common term for urticaria, are pink or red itchy rashes that may appear as blotches or raised red lumps (wheals) on the skin. They may be as small as the head of a pin, or as large as a dinner plate, and are often mistaken for mosquito bites. Hives usually last for up to two hours or may come and go for days or weeks at a time.

Hives occur when histamine is released in the lining of the skin and other body organs which makes the skin itch and causes blood vessels to expand and leak fluid. This results in redness and swelling.

Up to 20% of people will develop hives at some time in their life. In most cases hives are not due to allergy but usually respond well to treatment with antihistamines.

Q 2: Can hives occur anywhere else on the body?

Hives usually appear on the surface of the skin, but they can also cause deep, swollen areas under the skin and on the moist, inner lining of the nose and mouth (mucosa). This is known as angioedema. These swollen areas are often larger than the hives themselves, last longer, and are not as itchy.

Angioedema commonly affects the face and lips, can be painful, cause a burning sensation, and does not usually respond well to antihistamines. Although hives and facial swelling can be uncomfortable, they are not usually dangerous.

Q 3: What are common causes of hives?

It is not always known what causes hives, but they are rarely due to a serious disease. Some common causes are:

Infection from a virus is the most common cause of hives in children, especially if they last for more than 24 hours.
Contact allergy from plants or animals may cause localised (at the site of contact) hives.
Allergic reactions to food, medicines, or insect stings can appear as hives. They usually occur within one to two hours after exposure to the allergen and disappear within six to eight hours.

An allergic cause for hives should be suspected if episodes are rare, short-lived, and occur:

Only when exercising
Always within two hours of a meal and/or
When symptoms involving other organs occur around the same time, such as stomach pain, vomiting, difficulty breathing, or dizziness.

Hives lasting longer than a few days are unlikely to be caused by an allergy, except in some cases of drug (medication) allergy.

Stress is very rarely the cause of hives, but it can make symptoms worse. In some people, hives are caused by physical triggers including cold, heat, sunlight, vibration, rubbing, or scratching of the skin, and delayed pressure such as after carrying heavy bags or wearing tight clothing. In other people, exercise, sweating, stress, drinking alcohol or coffee, or eating spicy food may cause symptoms.

Q 4: Can hives indicate a severe allergic reaction (anaphylaxis)?

If hives occur with swelling of the tongue or throat, difficulty breathing or low blood pressure, this could be anaphylaxis. Anaphylaxis should always be treated as a medical emergency. Immediate administration of adrenaline (epinephrine), and medical assessment is required. Any delay can result in fatal anaphylaxis.

Q 5: What is chronic urticaria?

Chronic urticaria is when hives occur most days of the week for more than six weeks. Symptoms usually resolve, although this can take months or several years. Most people find non-drowsy antihistamines effective in managing the symptoms of chronic urticaria. Some people have more severe symptoms and need to be referred to a clinical immunology/allergy specialist or dermatologist for an assessment and other medications.

Q 6: When is testing needed?

Most people with hives do not need tests. When hives go on for a long time, or with unusual symptoms, it may be necessary to have some tests. Testing can also determine if allergy is a cause. It is important to exclude other diseases, which may look like hives at the start, but then develop into other conditions later. Hives that occur with high fever, bruising, bleeding into the skin, purple lumps that last for several days, or sore joints should be assessed by a doctor immediately.

Q 7: How are hives treated?

Hives usually get better within a couple of weeks without any specific treatment. Treatments include:

Avoiding aggravating factors such as excessive heat or cold, eating spicy foods, or drinking alcohol.
Avoiding aspirin and other non-steroidal anti-inflammatory drugs (NSAIDs) as they can often make symptoms worse.
Medications like non-drowsy antihistamines. These can be used to reduce the severity of the itch. For people with difficulty breathing and/or swelling of the tongue or throat, immediate administration of adrenaline and urgent medical assessment is needed.
Severe chronic urticaria sometimes requires a group of medicines called immune modulators or immunosuppressive medications which can reduce inflammation. Repeated use of cortisone/steroid tablets should be avoided due to the risk of side effects.
Special diets may play a role in the management of hives, but results are unpredictable and vary between people. Elimination diets under medical supervision, followed by medically supervised food allergen challenges may be useful in a small number of cases.

Content updated June 2024

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