[Safety of immunotherapy and skin tests with allergens in children younger than five years]. 
It has been demonstrated that specific immunotherapy, in addition to its preventive properties, is an effective and safe therapeutic resource for allergic asthma, allergic rhinitis and allergy to insect's venom; however, its use in patients younger than five years has been limited due to the risk of systemic reactions.  To know the frequency and severity of systemic reactions in children younger than five years and to know if a greater risk of systemic reactions in this group of age is real.  We included 239 patients from one to five years of age with diagnosis of allergic disease and verified its specific sensitivity with skin tests or RAST and were treated with specific immunotherapy.  A detailed registry of the application of specific immunotherapy was kept from every patient, with special attention to any symptom present during the first 30 minutes post application of specific immunotherapy or skin test.  From January 1996 to June 2005, 6,689 injections were applied to 239 patients.  Only one patient of 36 months of age presented with a delayed systemic reactions characterized by generalized hives, itching, runny nose, water eyes, 90 minutes post injection.  The patient was under treatment with Dermatophagoides farinae and pteronissinus (house dust mites) with a dose of 1AU for allergic rhinitis.  The systemic reactions were treated easily and without complications with a single dose of intramuscular epinephrine (0.15cc, 1:1000) and oral antihistamine.  Patients younger than five years are not in greater risk of systemic reactions from specific immunotherapy or skin tests than the older children or adults and the treatment of those systemic reactions does not imply greater difficulty.  Because of its preventive properties, safety and effectiveness in lowering the severity of symptoms of allergic diseases, we concluded that specific immunotherapy should be considered at early age, prescribed and administered only by specialist in pediatric allergy and in optimal conditions of safety.