Side effects due to allergic reactions to vaccine antigen or to additives such as chicken protein or gelatin have been known for some time. Recent findings regarding reactions mediated via the carbohydrate epitope galactose-alpha-1,3-galactose (alpha-gal), a constituent of animal gelatin, broaden the spectrum of gelatin-related allergies. This case series presents four patients who developed anaphylactic reactions following rabies vaccination using the vaccine Rabipur®. After appropriate allergy testing by skin prick testing and the determination of specific IgE to allergens in the vaccine, triggering by alpha-gal could be excluded and an allergy to gelatin was detected. The absence of allergic symptoms following the consumption of gelatin could potentially be explained through intestinal hydrolysis resulting in a loss of allergenic potency. Further implications related to the use of gelatin-containing infusions in emergency medicine are discussed.