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What is Urticaria or Hives
These are itchy raised bumps that can occur on the skin. They can look like individual small bumps, or may involve large patches of our skin.
They are warm and hot and extremely itchy. It may be sometimes associated with swelling of the eye and lips in what is known as angio-oedema.
On the microscopic level, what happens is that :
- There is sudden release of large amounts of histamine from our immune cells
- and that results in a sudden enlargement of small blood vessels within our skin
- followed by a rush of fluid out of our vessels into our skin causing an itchy swelling.
Urticaria is very common. About 20% of us would have experienced at least one episode of this at any time of our lives.
- If these hives are short lived, they are termed acute urticaria
- If they lasts for more than 6 weeks, then they are called chronic urticaria.
This is commonly seen in children.
Some of the common causes of acute hives are
- Fever and viral illnesses
- Reaction to allergens like dust or latex
- Parasitic infections like mites or scabies or insect bites
- Physical stimulations like sun exposure, or change in temperature from hot to cold or vice versa
- Less commonly : drug or food allergy
50% of the time, we may not be able to identiy any cause and that can be very frustrating for the child and parents
The hives comes and generally disappears within 24 hours but another batch of hives may appear in the same area or a different area. This process may repeat itself for many days or weeks. It can be so itchy that it may affect sleep and lessons or work.
- Antihistamines are the main treatment of choice
Some of the drowsy ones are piriton, diphenhydramine, hydroxyzine or promethazine The non drowsy ones includes Zyrtec, loratadine, telfast, aerius
In some instances doctors may even add in a different class of antihistamine like ranitidine or cimetidine.
- If triggers can be identified, the next course of action would be to treat the triggers or to avoid the triggers. This will possibly prevent the same thing from happening again.
If you have had hives before, keep hive medications in your medicine cabinet because hives tend to recur.
Hives that are of concern
Are there any signs which indicates that these hives are due to more sinister cause?
- If you notice that each individual spot lasts more than 24 hours OR
- They cause bleeding under the skin OR
- After the hives disappear your notice a brownish pigmentation that is left behind
Then you may need to see a dermatologist for a skinbiopsy to exclude the possibility of a vasculitis.
Otherwise in the large majority of cases, they are harmless.
By : Dr Chen Yiming
Family Physician, MBBS (Singapore), GDFM (NUS), GDFP Dermatology (NUS)