Local adverse reactions to vaccination are typically mild and often quickly resolve. Vaccine adjuvants such as aluminum salts in combination with improper vaccination technique may result in severe local adverse reactions. As far as we know, there is only one prior case of frankly necrotic rapidly progressing vaccine site necrosis, which occurred in a pediatric patient.1 To our knowledge, this is the first adult case of vaccine site necrosis to be reported. The presumed etiology has been aluminum salt adjuvants and improper vaccination technique. Here we present an adult case of a severe local reaction to a vaccine resulting in necrosis of the epidermis and dermis with central ulceration. Skin appendages were also involved, with necrosis of eccrine coils and hair follicles. This necrotic ulceration was likely due to robust inflammatory response to aluminum salt subcutaneous injection. Correct vaccine placement, needle size, and needle length may reduce adverse local skin reactions.