The only medical risk associated with allergy shots is an allergic reaction. The most common reaction is localized redness, pain and itchiness at the site of the injection. Systemic allergic reactions can also occur, but they are very rare. It is generally believed to occur in 1 per 100,000 injections. In addition, the majority of allergic reactions occur in the first 20 minutes, which is why we have patients wait for 20 minutes. As an extra safety precaution, we insist that all patients who receive allergy shots in our office carry Benadryl and an Epipen for at least two hours after receiving their injections.