Itchy Skin Rash - Urticaria

Urticaria is an itchy skin rash characterised by wheals (also known as hives). Wheals are areas of skin that are raised and they are usually red with a pale center. Urticaria is a manifestation of allergy.

The page addresses these questions:

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What is Urticaria?

Urticaria is an itchy skin rash caused by an allergic reaction that involves the skin. Urticaria is also known as hives.

It is often associated with angioedema which is swelling of the tongue and lips. 

In severe allergic cases, there may be an anaphylactic reaction which results in difficulty breathing and is life-threatening - to read more on anaphylaxis, click here 

Most urticarial reactions do not involve the life-threatening anaphylactic reaction.

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What does the urticarial skin rash look like?

The first thing that is noticed is usually intense itching. Then a rash appears and it is often raised. There are wheals, which are pale areas, and there is surrounding redness.

The raised areas (red with a pale center) can be anything from a couple of millimeters to several centimeters in diameter. Sometimes several smaller rashes join up to cause one large red raised skin rash (see the photos below of the trunk and of the arm where the rash has become confluent - so all joined together).

The main feature of urticaria is that it is an intensely itchy skin rash. The rash also changes so the rash comes and goes within hours. If the rash lasts in the same place for more than 24 hours, it is unlikely to be urticaria.

The photos below are all typical urticarial skin rashes. 

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What are the common causes of an urticarial reaction in children?

  • The most common cause is infection, usually a viral infection.
  • Food allergy (particularly peanuts, dairy products and fish) accounts for a smaller proportion of cases.
  • A few children get a reaction to medicines like antibiotics, or to insect stings, or parasites.

Urticaria in children is mostly acute and lasts less than 30 days. A smaller number of children will get chronic urticaria that lasts more than 30 days.

Urticaria close upUrticaria
Urticaria trunk rashUrticaria on trunk

The rashes in the photos above and below are typical urticarial rashes (hives). These were caused by a virus and the rash came and went for about 10 days, changing every day. The rash is raised with a central pale area and surrounding redness. This was an itchy skin rash, which was the main symptom bothering this child.

Urticaria confluent rashUrticaria confluent rash
Urticaria leg rashUrticaria leg rash

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How will I know what caused the urticarial reaction?

If the reaction is a IgE type of allergic reaction, you will often know as the reaction occurs quickly (10 - 15 minutes) after the trigger. To read more on allergic reactions, click here.

If you don't know what caused the reaction and this is the first time your child has had one, the most likely cause is an infection.

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What is the treatment of an itchy skin rash (urticaria)?

The treatment is antihistamines, such as:

  • loratadine (Alavert, Claritin)
  • chlorpheniramine (Chlor-Trimeton, Deconamine, Rondec, Piriton)
  • cetrizine (Zyrtec)

These are given for between 3 days and 2 weeks depending on response.

Steroids, such as prednisone or prednisolone, are often added to antihistamines. They are usually only given for 3 or 4 days.

In some cases, other anti-histamines called H2 blockers, such as Ranitidine, are given.

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Who gets urticarial rashes?

Anyone can have an allergic reaction but they often occur in children who have an atopic (allergic) tendency - this includes children who suffer from asthma, eczema and hayfever. The main feature of urticaria is it is an intensely itchy skin rash.

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Does my child need skin prick tests for allergy after an urticarial rash?

This is generally not necessary after one episode.

If a food is the cause, you will often know because your child had just eaten it before the rash appeared.

Skin prick tests are useful in children who continue to get urticarial reactions if a food is thought to be the culprit and confirmation is required.

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Does my child need Epinephrine (Adrenaline) at home?

If your child had an anaphylactic reaction which caused difficulty breathing or shock, she will require Epinephrine (Adrenaline) in an injectable form, such as a pen, at home.

If your child just had urticaria or angioedema (swelling of the tongue or lips), she will not need Epinephrine (Adrenaline) at home unless she also has severe asthma or you live remotely.

You need to discuss this with the doctor who saw your child when she was unwell.

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References

  • Mortureux P, Leaute-Labreze C, Legrain-Lifermann V, Lamireau T, Sarlangue J, Taieb A. Acute urticaria in infancy and early childhood: a prospective study. Arch Dermatol. 1998 Mar;134(3):319-23
  • Pollack CV Jr, Romano TJ.Outpatient management of acute urticaria: the role of prednisone.Ann Emerg Med. 1995 Nov;26(5):547-51.
  • Dershewitz R. Ambulatory Pediatric Care. Lippincourt-Raven. 1999
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Last reviewed 5 October 2011

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Dr Maud MD

Dr Maud MD (MBChB, FRACP, FRCPCH), a specialist pediatrician, provides health information and medical advice for parents of babies and toddlers. Read more about Dr Maud.



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