Subcutaneous allergen immunotherapy (SCIT) is an effective treatment for allergic rhinitis, asthma and venom hypersensitivity and has the potential of producing serious life-threatening anaphylaxis. Adverse reactions are generally classified into 2 categories: local reactions, which can manifest as redness, pruritus, and swelling at the injection site, and systemic reactions (SRs). SRs can range in severity from mild rhinitis to fatal cardiopulmonary arrest. Early administration of epinephrine, which is the treatment of choice to treat anaphylaxis, may prevent the progression of an SR to a more serious life-threatening problem. Although there is little debate about using epinephrine to treat a SCIT SR, there is a lack of consensus about when it should be first used. A uniform classification system for grading SCIT SRs will be helpful in assessing more accurately when epinephrine should be administered. The primary purpose of this article is to discuss the proposed grading system for SCIT SRs.