Urticaria (hives) is a skin reaction that can look similar to the marks caused by a nettle sting. A typical lesion can be a raised white plaque, surrounded by a red patch. It is thought that urticaria is a release of histamine and other mediators in the skin. Lesions can appear and disappear quickly within hours and is accompanied with itching. Urticaria can be acute or chronic and there are many causes.
Acute urticaria (hives)
An acute attack often occurs in an isolated way developing over a few hours, even a few days.
- This type of urticaria concerns up to 20% of the population.
- There may be an allergic cause: for example medicine, food, insect bites and latex.
Symptoms that last for more than 6 weeks or longer.
Causes can be immunological (allergic), non immunological (virus, temperature changes, sun exposure) or unknown.
Investigating chronic urticaria
There are numerous causes, making diagnosis quite complex. It can take many months to investigate and unfortunately, specialists only manage to find the cause of chronic urticaria in 20 - 30 % of cases.
- Primarily, symptom control is crucial, prescribing antihistamines, to prevent and treat attacks.
- Steroids and antileukotrienes are also prescribed.
Causes of chronic urticaria
- Allergies : are the most common cause of acute urticaria, which lasts for a few hours or days. They are seldom the cause of chronic symptoms.
- Some foods rich in histamine, like chocolate, shellfish, tuna or strawberries for example, can worsen chronic urticaria
- Medicines such as : aspirin, anti-inflammatory non-steroidal medication, morphine and codeine.
- Viral, bacterial infections, and parasites can also be at the root of the problem.
- <grasThyroid problems can also cause chronic urticaria.
- 60 - 70 % the cause is unknown.
Non -immunological causes of urticaria
Physical urticarias can be caused by scratching, heat, pressure, cold and ultraviolet light
- Dermographism is caused by scratching the skin: urticaria patches appear at the point of friction.
- Cholinergic urticaria is caused by heat, stress or effort.
- Delayed urticaria by pressure results in an oedema appearing after a firm pressure, on the forearm or the shoulders, while carrying a heavy object or under the feet after having walked for a long time.
- Cold urticaria
- Water or cold air, rain, snow, swimming in cool water can cause this type of urticaria.
- Violent reactions, like abdominal pains, an asthma attack or an anaphylactic shock have been observed.
- A test conducted in hospital by applying an ice cube to the forearm can confirm the diagnosis.
- The cause of this urticaria is generally unknown, without a specific cause, or is sometimes linked to a virus.
- Care needs to be taken when swimming, both at sea or in a swimming-pool and to not to bathe alone, without being monitored.
- In case of a severe reaction, it is crucial to have the appropriate medication to hand, such as steroids and adrenalin in order to avoid further complications.
If cold urticaria is suspected then specialist help is crucial and getting the correct diagnosis vitally important as an attack could be life threatening.
- Solar urticaria It occurs in the first minutes after sun exposure and disappears quickly after sitting in the shade.
Ask a doctor for advice on exposing your skin to the sun.
Urticaire - Crise d'urticaire