Urticaria is a common disease and the symptoms are familiar to most people: red, itchy swellings on the skin (wheals) which appear all of a sudden and disappear just as quickly, only to appear few hours or days later in another place on the body.
Urticaria seems simple, however, people suffering from it and the doctors treating them know how difficult it often is to deal with. There are many reasons for this:
Acute and chronic spontaneous urticaria are the most common forms of urticaria, with symptoms occurring “out of the blue” without an evident triggering factor (most people think it’s an allergy to food but in reality this is rarely the case). Some people experience urticaria when they rub or scratch their skin. This is called dermographism (in Latin this means “writing on the skin”). Other people develop urticaria symptoms when their skin is exposed to cold – cold induced urticaria – or when their body becomes heated, such as when they sunbathe or take a hot bath; this is called cholinergic urticaria.
Acute urticaria may last from several hours up to six weeks. Most often it is caused by a viral infection (usually you get the infection first with urticaria following after a few days). Drugs such as penicillin and aspirin are another frequent causes. In children, allergy to milk and eggs can sometimes take the form of acute urticaria. However, in adults, food allergy is only rarely involved in urticaria.
Urticaria is called chronic if the symptoms last for longer than 6 weeks. Sometimes the symptoms can last for months or even years which is why people are more concerned with chronic urticaria than with acute urticaria.
Similar to acute urticaria, chronic urticaria is almost never caused by a true allergy. Most often it is caused by:
Chronic Infections (of the throat, teeth, sinuses, lungs, stomach, intestines, kidneys etc)
Pseudoallergens in Foods substances in foods which can trigger the same events and the release of the same substances as in allergy but without the need for IgE antibodies (the allergy antibodies) to mediate their action. Pseudo-food allergens can be preservatives, anti-oxidants, colorants and flavour enhancers in foods but also naturally occurring substances in fruits and vegetables (such as tomatoes, peppers, olives, nuts etc).
Abnormal Antibodies that are directed against the immune cells and activate the same events as in allergy but in an IgE independent manner (these are also pseudo-allergic reactions).
Chronic idiopathic urticaria: in a number of cases the cause of urticaria cannot be identified.
The simplest way to prevent urticaria is to avoid the factors that cause it. However, finding out which is the initial cause or the triggers of urticaria can be a very difficult task, requiring a lot of time, and many investigations and patience from both the doctor as well as the patient. Sometimes one can find the answer only after several attempts. Sometimes the cause can never be found, despite all efforts. Many sufferers can be helped by regular treatment, often with antihistamines.
Even if the cause of your problems is not found, a diet low in pseudo-allergenic foods and also avoidance of drugs known to cause pseudo-allergic reactions (such as aspirin and other painkillers) might be helpful. Talk to your doctor about this.
Sometimes local swellings beneath the skin occur together with urticaria. These are sore rather than itchy, but are usually caused by the same process as urticaria and are rarely problematical. Angioedema, occurring without any urticaria, can have several causes and needs investigation since occasionally the airway can be involved with difficulty in breathing. A common cause is a class of drug used to treat high blood pressure known as ACE inhibitors. If you have angioedema and are taking these you should stop them and consult your doctor immediately.
Contrary to popular belief, urticaria is rarely caused by an allergy. In most cases urticaria is a false allergy i.e. it involves the same immune cells and the same events as allergy except the triggers do not act through the IgE antibodies but are activated directly by the immune system.
Food allergy is rarely a cause for spontaneous urticaria. On the other hand, pseudo-allergens in foods are commonly involved in urticaria, probably less often as an initial cause but very often as triggering factors.
If the cause of your symptoms is not evident you can keep a diary where every day you record the symptoms you have experienced, all the foods you have eaten (also all the drinks), the drugs you took, the places you have visited or the activities you were involved in.
A 2-week course of a pseudo-allergen free diet seems to prevent or improve the symptoms in more than half of patients with chronic urticaria.