Rashes - Urticaria

Urticaria is a medical term given to the appearance of hives or wheals on the skin. 

It is a common skin condition affecting up to 20% of people (one in 5 people) at some point in their lives.  The rash is due to release of a chemical called histamine.

People often mistake these rashes for allergy, but in fact 90% are not caused by allergy.

The urticarial rash consists of pink or white raised areas of skin resembling nettle rash, which are called wheals. It is usually itchy. The wheals are often round or ring-shaped. 

Wheals can also appear as lines when the skin is firmly stroked.

Hives/wheals can appear anywhere on the skin.  Individual wheals typically dispaper of their own accord within 24 hours but new wheals can continue appearing on a regualr basis for a number of days, and can last ofr 8-10 days. 

Sometimes hives can be associated with swelling, most commonly of the lips, eyes, hands or feet.  This is termed as 'angioedema'.  it is not usually itchy and can take over 24 hours to clear.  Some people develop mostly hives, some mostly swelling, and others a combination of both. 

When urticaria is caused by a food trigger it ususally starts shortly after the child has eaten the food: typically within 1 hour. Only suspect food allergy if the rash occurs within an hour of eating a new food, or occurs every time a specific food is eaten. 

Half of the time children will develop the rash due to a virus such as the common cold, flu or COVID.

For many children there is no clear reason why the rash appears, but it typically settles down with time. 

Occasionally urticaria can be due to allergy to something in the environment (e.g. pollen), insect stings or medicines, but we would expect the rash to only occur when they have come into contact with these and not at other times.  

Usually, the appearance of the rash will be enough for your doctor to make the diagnosis and in majority of the cases it does not need any investigations or tests. 

Urticaria does not ususally affect their general health, but the appearance of ther ash and the itch itself can be distressing.  As a rule, urticaria tends to improve and become less troublesome over time. 

Antihistamines: You can buy these over the counter:

• 1 - 2 years - Chlorphenamine (Piriton)
• 2 years and over - Cetirizine or Loratadine
• Whilst you/your child has the rash give the antihistamine regualrly according to the instructions on the medicine.  If needed, Cetirizine can be prescribed by your GP to children over 1 year, or Fexofenadine can be prescribed for children over 6 years.

Topical treatments: For some children menthol containing creams can help the itch.

Most episodes settles within 7-10 days.

Some children are prone to recurrent hives - if these last longer than 6 weeks we call this chronic urticaria.