Immunotherapy is a long-term treatment which helps reduce your body's reaction to allergy. It contains a small amount of the allergy that you are allergic to - this helps your body to overcome your allergy by teaching your immune system to react to pollen in a more normal way.
This education of your immune system takes time, but results have the potential to last after treatment has stopped.
Immunotherapy may be particularly helpful when antihistamines and/or nasal sprays have failed to adequately control your allergy symptoms.