Urticaria is a rash, which usually comes on fairly rapidly, sometimes over a few seconds. The rash is similar in appearance to the red weals that appear after contact with stinging nettles (Urtica Diosis ), after which the condition is named. The rash is raised and usually very itchy. It is caused by the release of substances such as histamine, into the skin. The commonest identifiable cause for urticaria is an allergic reaction, but other factors such as infection, physical stimuli and various diseases may be involved. The commonest situation, however, is where no actual cause of the urticaria can be identified. Acute allergic urticaria is quite common and usually results from eating food to which the individual is allergic, typically shellfish, eggs, nuts and fresh fruits, such as strawberries but it may result from any kind of contact or the sting of an insect. In angioneurotic oedema, the swelling may affect lips, mouth and tongue. This latter may cause acute blockage of the airways, which can be fatal. Some cases of allergic urticaria can progress to this state rapidly and one, particularly dangerous, is nut allergy because nuts appear in so many forms (often not labelled) in so many foods. Chronic urticaria is a non-allergic condition, which can be very irritating and may last for years. Urticaria can also be caused by pressure, in some cases simply by stroking the skin firmly (dermatographia), by heat, cold, sun, water, and infection.

It is essential – though it might not be found – that a cause for the urticaria should be sought. The food that, that on the first occasion gave an individual “ hives”, may, next time, kill them. Skin tests can be carried out that will determine the factors causing the allergy, the allergens, involved. These tests, which, themselves, are not without hazard, should be carried out in the skin departments of hospitals. They cannot be carried out on samples of the person’s hair sent through the post or by a non-physician in a health store. Once found, the cause can be avoided, if possible. This can, sometimes, be very difficult. Particularly with nut allergy in children. Small children will usually eat anything given to them and nut products are found, as said above, very widely, in all types of food and confections. Desensitisation injections are not used as much as they were in the past as they have their own dangers. The commonest treatment of all urticaria is antihistamines. In some more severe cases, steroids are prescribed. In the most severe form of urticaria/allergy where obstruction to breathing occurs, emergency medical attention should be sought, and adrenaline, by injection, will be given. A person who can judge his, or her, condition may be given an adrenaline injection to carry at all times which can be self-administered.