Decongestants decrease swelling in the nose. Immunotherapy is a process whereby the allergic mechanism underlying allergic rhinitis is modified. Immunotherapy typically involves once or twice-weekly injection of the allergens to which the patient is allergic. Initially a dilute solution is used and then the concentration is increased gradually until the highest level that can be injected without causing significant local reactions is reached. After about one to two years of injections, about 80 to 90 percent of patients have a marked reduction in symptoms.
Immunotherapy works well for allergic asthma and stinging insect sensitivity as well.
Overall, everyone with allergies should be instructed on allergy avoidance techniques and receive some symptom-reducing medication. It is recommended that patients with significant symptoms for four or more months per year, who cannot avoid their allergens and for whom medications are inadequate, could be candidates for immunotherapy. Probably, no more than 20 to 40 percent of patients require allergy immunotherapy for control. There is at least one death per year in the United States as a consequence of immunotherapy. Proper immunotherapy requires that injections contain substantial amounts of allergen and therefore are potentially dangerous.