Acute supraglottitis is a medical emergency as it can rapidly lead to airway compromise. With routine pediatric immunization for Hemophilus influenzae serotype b, supraglottitis is now more prevalent in adults, with a shift in the causative organisms and a change in the natural history of this disease. Here, we present a case of supraglottitis due to group B streptococcus that occurred in an adult with previously undetected immunoglobulin 4 (IgG4) and complement protein C2 deficiency.