Allergy shots, also known as subcutaneous immunotherapy, is the historical route of administration and consists of injections of allergen extract, which must be performed by a medical professional. Subcutaneous immunotherapy protocols generally involve weekly injections during a build-up phase, followed by monthly maintenance injections for a period of 3–5 years.
They are given under the skin (often in the upper arm) usually at the doctor's office.
One or more shots each time the patients go to the doctor's office: Once or twice a week for the first few months; Once or twice a month after that.
3 to 5 years (or sometimes longer).
Common side effects of allergy shots include:
Itching, swelling, and redness at the place where the shot was given
Mucus dripping down your throat
Although efficacy of subcutaneous immunotherapy has been demonstrated by several studies, it entails the risk of systemic anaphylactic reactions Hence the necessity for it to be performed by clinicians trained in allergy.