Immunotherapy involves giving gradually increasing doses of antigens to patients with allergies that affect their safety or quality of life. Eventually, immunotherapy causes the patient’s allergic response to disappear or decrease to a negligible level. Once this happens, the immunotherapy can be discontinued.
Many patients don’t realize is that it is possible for an allergic reaction to return many years after immunotherapy has ended. If this occurs, immunotherapy may need to be repeated. Because it has been done before, however, the second round of treatment should be much shorter.
If you have had immunotherapy for severe allergic reactions, be aware that in 8 to 10 years your allergic reactions could possibly return. To be on the safe side, you may need to be retested, to see if more immunotherapy is needed.