Updated September 2024
On this page
What is urticaria?
Urticaria, commonly known as hives, are pink or red rashes that look like lumps (wheals) or blotches on the skin. They are often very itchy.
Urticaria happens when chemicals, such as histamine, are released from mast (immune) cells in the skin. These chemicals cause small blood vessels in the skin to leak fluid, resulting in lumps/wheals forming. The chemicals can also make the skin around the wheal red and feel itchy.
Up to 20% of people may have urticaria at some time during their life and in most cases, urticaria is not due to an allergic reaction. To see photos of what urticaria looks like click here.
What does urticaria look like?
It is important to know that urticaria can look the same no matter the cause. Urticaria that happens in an infection can look the same as the skin symptoms that might happen during an allergic reaction. Being aware of what was going on at the time the urticaria appeared and how long it lasted may help doctors decide the possible cause.
Urticaria can look like a mosquito bite but can also come in all different shapes and sizes. Wheals can be as small as a pinhead (a few millimetres) or as large as a dinner plate (several centimetres). The wheals may be round, oval, rings and patches and can change as the rash develops. The wheals are often white/pale colour surrounded by red skin (flare) around the lump.
Some people might only have a few wheals on one part of their body, while other can have hundreds of wheals all over.
Angioedema
Sometimes people with urticaria develop swelling in the deeper layers of the skin, this is called angioedema. Angioedema usually affects the face, lips and skin around the eyes and often feels tight or painful rather than itchy. It can appear alongside urticaria but can happen on its own. Angioedema may last longer than urticaria as the swelling is more severe so it takes more time for the extra fluid to go away.
How long does urticaria last?
Urticaria can last for minutes, to hours and some can last from days to weeks. How long urticaria lasts depends on the type of urticaria it is.
Types of urticaria
Acute urticaria
- This may be a one-off episode which goes away within a few hours or it may last for a few days or weeks (less than 6).
- This is the type of urticaria that is seen in an allergic reaction to food, medicine, or insect stings.
- It can also be caused by skin contact with things like plants or animals.
- Non allergic causes of urticaria include infections, such as a virus, especially in children.
Chronic urticaria
- Is not a one-off episode.
- Wheals may come and go but continue to reappear or remain.
- This type is not caused by an allergic reaction.
- The cause may be known or unknown.
Acute urticaria
Urticaria due to allergic reactions:
- Urticaria can be a sign of a mild to moderate allergic reactions to food, insects, medicines or other allergens.
- Urticaria due to allergy will usually appear within 2 hours of being exposed to the allergen.
- Urticaria alone is not life threatening. Use an ASCIA Action Plan to manage the reaction and watch for any one sign of anaphylaxis. If there are any signs of anaphylaxis treat as an emergency – do not shower.
- Will usually go away in a few hours.
If you think urticaria was caused by an allergy:
- See a doctor to confirm this.
- Having a list of what was put into the mouth or activities done in the 2 hours before the urticaria appeared may help your doctor decide whether allergy is a likely cause. ASCIA has an Event Record for Allergic Reactions that can be filled out and given to your doctor when you see them.
- Take photos as the urticaria might be gone at the time of your appointment. Photos may help your doctor confirm the diagnosis.
- Allergy testing may be needed.
Chronic urticaria
There are two types of chronic urticaria:
- Chronic spontaneous urticaria: Wheals appear without an obvious cause on most days of the week for six weeks or more. The wheals may come and go and can appear anywhere on the body. There may also be swelling or angioedema.
- Physical urticaria: Wheals are caused by a known physical cause. This may include scratching or friction (dermographism), cold (cold urticaria), sunlight (solar urticaria), increased body heat (cholinergic urticaria), pressure (delayed pressure urticaria) or vibration. People with physical urticaria do not react to all of the causes listed, often they only react to one.
Note: Urticaria from cold can be severe, especially when swimming in cold water. Some people have been known to have symptoms of anaphylaxis due to cold urticaria.
People with chronic urticaria should be under the care of a doctor with specialist knowledge of this condition.
Treatment of urticaria
- Cool, wet cloths put on the affected skin may help to reduce itch and discomfort.
- Non-drowsy antihistamines are a good treatment for hives. They won’t cure the hives, but help to lessen severity and itch. People with chronic urticaria may be advised to use them by their doctor to help reduce symptoms happening so often. Read more about antihistamines here.
- Note: If antihistamines do not work, you should speak to your doctor, especially if symptoms are severe and you feel unwell.
- Severe chronic urticaria sometimes requires medicine that reduce inflammation, called immune modulators, immunosuppressive medications, or steroids.
- Special diets are not usually recommended for treating chronic urticaria. Unfortunately, it is difficult to tell who will respond to diet-based treatment. A short-term elimination diet under close medical supervision, followed by food challenges may be useful in a small number of adults.
Management of urticaria
Most urticaria go away within 2 weeks without any treatment and management depends on the type of urticaria.
For urticaria caused by allergy:
- Avoid allergens.
For chronic urticaria:
- Follow specific management advice from your doctor.
Some people find the following may help reduce symptoms:
- Cooler shower temperature
- Wearing loose-fitting clothing
- Avoiding or reducing amount of alcohol
- Avoiding or reducing amount of coffee
- Reducing stress levels where possible
- Not taking aspirin and other non-steroidal anti-inflammatory medicine (NSAIDs) – speak with your doctor about this.
When to seek help
Emergency – straight away
If there are any of the symptoms listed below, follow the instructions on the ASCIA Action Plan and call triple zero (000) for an ambulance:
- Difficult or noisy breathing
- Swelling of the tongue
- Swelling or tightness in throat
- Wheeze or persistent cough
- Difficulty talking or hoarse voice
- Persistent dizziness or collapse
- Pale and floppy (young children)
For more information see Emergency Treatment Now – Having an allergic reaction.
See a doctor soon
Urticaria does not make you sick. If you have urticaria and are sick with a high fever, weight loss, sore joints, or bruising, see your doctor as soon as possible. Sometimes blood tests will be recommended to exclude other diseases.
Mental health
Having chronic urticaria can affect quality of life and the ability to participate in everyday activities. Speak with your doctor, this could be your GP or specialist, about how your condition is affecting your mental health and seek help if needed. You may wish to call Allergy & Anaphylaxis Australia to speak with an allergy educator – for more information click here.
For urgent 24 hour mental health support:
- If a life is in danger – call triple zero (000)
- Lifeline Australia – 13 11 14 – Crisis Support. Suicide Prevention
- Mental health helplines | Healthdirect
Signs and symptoms of an allergic reaction
Learn about the signs and symptoms of allergic reactions, and the difference between a mild or moderate reaction and a severe reaction (anaphylaxis).
Related information
Types of allergies
Learn more about the different types of allergic disease including diagnosis, triggers and treatments and about allergic reactions.
Living with allergies
Learn more about daily life with allergies – including reading labels and ingredients, managing different environments and what to do if you or a loved one has an an allergic reaction.