Immunotherapy (or desensitisation) is a treatment that is used when medicine is ineffective such as for severe hayfever or life-threatening reactions to wasp or bee stings. The therapy builds up tolerance to the allergen that your child is reacting to.

Your child will be given increasing amounts of the allergen as injections just under the skin. This tricks the immune system into tolerating the allergen so your child is no longer allergic to it. This usually involves weekly visits for four to ten weeks depending on the problem. For most conditions, monthly injections are then required for three to five years to maintain the protection. During this period, the treatment becomes more effective.

As the treatment involves giving an allergen that your child is allergic to, the main side effect is an allergic reaction. These are usually minor and localised to the injection site.

There is a small chance of a more severe reaction so injections are always given in hospital and children have to stay on the ward for an hour before they are allowed home.