Also known as allergy shots, subcutaneous allergen immunotherapy is a treatment in which gradually increasing doses of an allergen are injected under your skin. An allergen is a substance that can bring about an allergic reaction. Pollen, dust mites, and pet dander are the most common examples of these substances. When you receive an allergy shot, your body produces "blocking" antibodies that decrease your immune system's sensitivity to an allergen, thus reducing your symptoms.
Before treatment is begun, you and your doctor first have to identify different factors that trigger your symptoms. Then, skin tests are done to confirm which substances cause allergic reactions. Blood tests may be performed as well, but they are typically not necessary.
There are two phases to subcutaneous allergen immunotherapy: a build-up phase and a maintenance phase. The build-up phase lasts three to six months, during which you receive shots with increasing amounts of the allergens once or twice a week. When the effective dose is reached, the maintenance phase begins and may continue for up to five years.
Although allergy shots are the longest-lasting and most effective allergy treatment available, they are not for everyone. If you have heart problems, high blood pressure, or severe asthma, you should not be given allergy shots. The injections are generally safe, but you may have a little swelling at the injection site, which is normal. Rarely, severe shock-like reactions, called anaphylaxis, can also occur. You will likely be required by your doctor to stay for half an hour after your shot, so in the event of an anaphylactic reaction, it can be treated immediately.