Background: Recent studies demonstrated that, in the past few years, the number of jellyfish species is increasing worldwide; this increase can be explained by environmental and climatic reasons. Contacts with jellyfish can cause acute and chronic effects, including allergic reactions. Although anaphylaxis caused by jellyfish is a rare event, repetitive stings during bathing as well as marine sports and job activities represent important risk factors that can increase the probability of sensitization. Recently, it was also pointed out the possibility of anaphylaxis caused by jellyfish ingestion. In these cases, the sensitization could also be related to previous stings. In cases in which there is no history of jellyfish contact or ingestion, it has been hypothesized that there is a sensitization to an unknown cross-reactive antigen. Objective: The purpose of this work was to collect and review published studies and cases of anaphylaxis associated with jellyfish. Methods: We performed a medical literature data base search, which included English language articles published until September 2019, by using the key words "jellyfish" associated with "anaphylaxis" or "anaphylactic shock." Results: The results of our research showed that dangerous reactions can be caused both by contact and ingestion. Moreover, the latest changes in food habits, life style, and globalization could lead to a more frequent exposure to jellyfish both by contact and ingestion, and, consequently, to a higher probability of sensitization. Conclusion: Prospective studies and well-structured research are needed to better understand all the potential immunologic elements of jellyfish, to clarify its role in sensitization, and to avoid possible dangerous allergic reactions caused by cross-reactivity.