What are hives?

Hives (also called urticaria, welts or wheals) are itchy, raised swellings on the skin. They are usually pink or red and can appear anywhere on the body. The swellings can range from small to large and may come in different shapes.

Hives often disappear within 24 hours. Sometimes, the rash can last for weeks.

What causes hives?

Hives can be triggered by many different things. Common triggers include:

• insect stings or bites
• medicines — such as antibiotics or anti-inflammatory medicines (NSAIDs)
• food allergies — especially to peanuts, other nuts, strawberries, cow's milk, fish, shellfish and eggs
• contact allergens (allergies that happen when an allergen touches your skin), such as latex
• infections
• conditions that affect your immune system
• stress
• physical factors — such as cold, heat, pressure, vibration, exercise or sun exposure

You might not know what triggers your hives.

When should I see my doctor?

See your doctor if you have:

• a rash that looks like hives
• hives that don't go away or keep coming back
• taken antihistamines for your hives but they do not control the symptoms

If your child gets hives repeatedly, it's important to see their doctor. This could indicate an allergy to something in their diet, and your doctor will help you try to find the cause.

When to seek urgent care

Sometimes hives can be signs of something more serious:

• Angio-oedema — swelling under the skin, often around the lips, face, neck or throat. If it blocks the airway, it is an emergency.
• Anaphylaxis — a severe allergic reaction that can lead to trouble breathing, swelling or dizziness. This is life-threatening and needs urgent treatment.

How are hives diagnosed?

Doctors usually diagnose hives by looking at your skin. They will ask questions to try to find the trigger. Hives usually don't need tests.

They will also rule out emergencies, such as severe allergy (anaphylaxis) or trouble breathing.

If you have hives that last a long time and there's no clear cause, blood and urine tests may check for other conditions. Your doctor may refer you to a specialist.

How are hives treated?

Hives usually get better without treatment. If you do need treatment, it will depend on what is causing them and how severe they are, and how your body reacts.

Self-care at home

If you know what causes your hives, try to avoid triggers. You can also use a cool compress or bath, or apply calamine lotion to help relieve the symptoms.

Avoid alcohol, as this can also worsen symptoms.

Medicines for hives

Medicines for hives include antihistamines, which may be helpful if your symptoms don't go away after a few days.

You can buy these medicines over the counter at a pharmacy. Ask your pharmacist which antihistamine is best for you, as some may cause drowsiness.

If your hives do not respond to antihistamines, your doctor may suggest other medicines.

What are the complications of hives?

Hives can sometimes lead to complications such as reduced quality of life. Scratching and itching may disturb sleep and daily activities. People with chronic urticaria may feel anxious and stressed, and flare-ups can limit work, school or social life.

If hives are causing sleep issues or making you feel anxious, let your doctor know so they can adjust your treatment as needed.

Can hives be prevented?

If your hives are caused by a specific trigger, such as a food or medicine, you should avoid your known triggers.

If you don't know what is causing your hives, it may be difficult to prevent.

Resources and support

• For more information about the causes and management of hives see the Australasian Society of Clinical Immunology and Allergy website.
• Allergy and Anaphylaxis Australia has more information on hives.
• The Royal Children's Hospital has a fact sheet on hives for parents to learn about care at home and more severe reactions.
• The Sydney Children's Hospital Network has information on hives in children.

You can also call healthdirect on 1800 022 222 at any time to speak to a registered nurse (known as NURSE-ON-CALL in Victoria) for more information and advice.