If no reactions occur, the amount of allergen in each shot is increased until a maintenance dose is reached. For a very sensitive patient, the maximum dose may be the amount the patient can tolerate without a reaction. Others may be able to reach a predetermined amount that researchers have found to be necessary for optimal allergy relief. Once the maintenance dose has been reached, the intervals between shots can be gradually increased to two, three and even four weeks apart. Reaching the maintenance dose can take anywhere from six months to three years.
Patients receive increasing doses of the allergens several times a day for three or four days.
This requires close medical observation because the frequent schedule greatly increases the risk of anaphylaxis. That risk, plus the inconvenience of spending several days all at once at the doctor's office or in a clinic, makes rush immunotherapy unpopular with many patients and physicians, says Yunginger. It is usually necessary to continue shots for a couple of years at least, but the idea is to continue only if the treatment is effective, not just in the hope that someday it may help. Fruitless treatment should not drag on for years. Anywhere from three to five years of treatment is the usual recommendation, says Yunginger.