A B C D E F G H I J K L M N O P R S T U V W

URTICARIA

What is Urticaria ?

Urticaria is a very itchy skin rash which comes and goes. To start with, there are just one or more areas of redness on the skin. These areas then swell up, and there is blanching of the skin. Individual areas of the rash last a few hours and then subside. These can later be replaced by new areas.

How does Urticaria occur ?

The rash is caused by the release into the skin of a chemical called histamine. This comes from certain cells called mast cells which are abundant throughout the skin. It is the release of histamine which causes initial redness.

Why does Urticaria occur ?

In most patients, urticaria is due to an allergy to a "foreign" substance either taken by mouth or entering through the lungs. The body reacts to this substance by making a chemical called an antibody. This particular antibody (called IgE) joins together with the substance. Together, they pass through the blood-vessels into the skin where they link on to the mast cells. It is this link which causes the mast cell to release the histamine into the skin. Urticaria may also be part of a more widespread disease such as systemic lupus erythematosus or vasculitis. Certain drugs, particularly those containing salicylic acid (like aspirin) and opiates, can have a direct effect on mast cells. This causes them to release histamine without it being a true allergy. Most patients who have urticaria are allergic to a food substance. It takes the body some time to develop an allergic response to a particular substance. This is why urticaria can develop at any time in your life. The particular foodstuff may be easily identified: shellfish, strawberries and citrus fruit, for example. In general the allergy is to something that is more widespread, such as a preservative or an additive. This makes it extremely difficult to identify what is causing the allergy. It is also very common to develop urticaria as an allergic response to certain drugs, particularly antibiotics.

Treatment Involved for Urticaria

Unfortunately, there are no tests that will allow us to identify exactly what substances you are allergic to. In general, if it is not apparent to you what is causing the urticaria, exclusion diets and skin tests will be of very little value. It is certainly worthwhile keeping a diary to see when the urticaria comes up. You may be able to relate it to something that you have eaten or drunk. Blanket restrictions of various foodstuffs tends to be unproductive. Treatment consists of the use of antihistamines. These need to be taken regularly, rather than just when you have the itch. They should control the rash completely. Once you have been symptom free for a period of a few days, you can try stopping the tablets to see whether the urticaria returns. If it does, you need to continue with the antihistamine. If it does not, then the urticaria has resolved of its own accord.

During Treatment

Many antihistamines have a sedative effect, even without taking excessive doses. This sedative effect is aggravated by alcohol. It is better not to drive and to avoid alcohol while on the drug. The newer antihistamines including terfenadine, astemizole, cetirizine and loratadine have less of a sedative effect and are therefore better tolerated than the older types.

After Treatment

In an individual person, it is impossible to predict how long urticaria will last. In all patients, urticaria does go away by itself eventually. Because you will be completely free of symptoms while taking antihistamines, you will not know when the urticaria has resolved. It is therefore important to stop the antihistamines every now and again to see whether the rash does come back. Always tell any new doctor whom you see that you have urticaria, so that any of the unsafe drugs such as salicylates and opiates can be avoided. Taking any of these drugs could cause a massive attack of urticaria. Such an attack could not only affect the skin but also the lungs and the windpipe (trachea and larynx). This could cause serious breathing difficulties and could even be fatal. Once urticaria has settled down, it often will not come back even in response to the same "trigger" substance. However, you may develop allergies to other substances, causing further attacks later in life.

If Urticaria is left Untreated

Urticaria is a self-limiting condition and would eventually resolve of its own accord. It can however cause enormous distress and may seriously affect the quality of life of an affected person. Treatment with antihistamines is very safe, particularly with the newer non-sedating antihistamines, which should cause few side-effects. Be sure that you let a new doctor know that you have urticaria: a wrong drug could cause a serious and dangerous attack.