5 years. Most people see results in as little as 9-12 months, and nearly maximum results by three years, and a full course of therapy is 5 years. Symptoms often start to come back three to five years after stopping immunotherapy, so some patients prefer to continue the shots for much longer than 5 years.
Immunotherapy-Time? With immunotherapy ("allergy shots"), small amounts of allergy extracts, like pollens, house dust, and pet danders are injected usually once or twice a week to start, and slowly increased to avoid systemic or large local reactions. It typically takes 4 to 6 months for the shots to start working. Once a stable (maintenance) dose is reached, they are continued for several years, every 2-4 weeks.
How long. I have ssen it work fairly quickly weeks to months in younger individuals. Longer in some than others.