Immunotherapy is the only treatments for allergies that can prevent the natural tendency of allergies to progress in severity and duration each year. It is effective in approximately 70-80% of allergic cats.
Immunotherapy consists of a weak solution of whatever a patient is allergic towards and is available as both the traditional injections under the skin, or as an oral spray (sublingual immunotherapy).
The advantage of treatment with immunotherapy is the safety of this treatment plan, with the only significant side effect being a very rare incidence of an allergic reaction to the immunotherapy itself. Immunotherapy can therefore be used lifelong without fear of long-term side effects.
The disadvantage of immunotherapy is that it does take a while to take effect. The average time to response is 4-6 months, but it can take up to one year to become effective. If immunotherapy proves to be effective after a year, as with other therapies, it is typically continued lifelong to manage allergies in most cats, though a small percentage may achieve "cure" and be able to have the treatment discontinued eventually.
