Immunotherapy
When someone asks how long allergy treatment takes, they are really asking two questions. First, they are wanting to know how long it will take before they see improvements, and secondly, they are asking how long before they can stop treatment (shots, drops, medicine, etc.) without having any symptoms.
The first question is the one that is harder to answer because everyone is different. Some people notice a drastic difference within the first week of treatment, while others may not notice any improvement until months after starting treatment. The rate of treatment also affects how long it takes to improve. For example, some people will be able to get two shots per week, while others only can only handle one shot per week. Some people will get mild reactions to the shots and have to slow down the progression, while others may have no symptoms and are able to progress through the treatment more quickly. However, every patient should be seeing some improvement within six months of starting treatment, at the latest, and should notice drastic improvement within 12 months. If they are not seeing improvements, then the treatment will likely need to be adjusted.
For the second question, it is more straight forward. After 6-12 months of allergy testing, your symptoms should be greatly improved. It is recommended that treatment be continued for a total of 2 years, though treatment can be continued for up to 5 years. After discontinuing treatment, your allergies should remain under control for another 2-3 years without any shots or medications. So in theory, a patient could receive 2 years of treatment, discontinue treatment after 2 years, and continue to enjoy the benefits for another 2-3 years for a total of 5-6 years of relief. As stated, the longer you remain on shots, the more benefit you will receive and the longer the effects of the treatment will last.