Uterine Anaphylaxis Due to Subcutaneous Immunotherapy (SCIT) for Inhalant Allergens: A Case Series

Subcutaneous immunotherapy (SCIT), commonly known as "allergy shots," aims to achieve a clinical tolerance for allergens that cause symptoms of allergic rhinoconjunctivitis, allergic asthma, or insect sting allergies. Systemic reactions to SCIT are classified in severity from one organ system (grade 1) to anaphylaxis that potentially may have a fatal outcome (grade 5). Uterine cramps fall under grade 2, and they are rarely reported during SCIT. In this study, we report four cases of uterine anaphylaxis following SCIT for environmental allergens with symptoms such as severe lower abdominal cramping resembling menstrual cramps. Patients also experienced urticaria, angioedema, diffuse erythema, and flushing. None of the patients experienced uterine bleeding. To the best of our knowledge, this is the largest case series reporting this reaction to SCIT. We accompany this finding with a review of the literature on this rare but interesting topic.