Introduction: In Guadeloupe, numerous cases of marine poisoning are reported, particularly those caused by jellyfish, whose stings can lead to Irukandji syndrome (IS). The objective of this study was to analyze the clinical characteristics of IS based on cases of envenomation received in the emergency departments of the two public hospitals in Guadeloupe, and to compare IS cases with cases of simple stings. Methods: All cases corresponding to jellyfish stings were extracted from emergency department databases between January 1, 2010, and September 1, 2016. SI was defined as reported contact with a jellyfish and at least one of the following signs: headache, nausea, anxiety, vomiting, sweating, agitation, muscle cramps in all four limbs, or severe lumbosacral or thoracoabdominal pain. Results: Two hundred and eleven envenomations were recorded, of which 45.0% occurred between the 22nd and 26th lunar days of the months of June through September. Ninety-five patients had SI, of whom 3 presented with angioedema and 1 with cardiac decompensation. Other clinical signs were associated with SI compared to simple sting cases: hypertension (51.6% vs. 18.1%, p < 0.001), tremors (32.6% vs. 14.7%, p = 0.0014), paresthesia (20.0% vs. 10.3%, p=0.049), dyspnea (13.7% vs. 3.4%, p=0.006), and pain intensity on the visual analog scale (7.5 ± 2.6 vs. 6.0 ± 2.6, p=0.001). Discussion and Conclusion: In Guadeloupe’s emergency departments, jellyfish stings were frequently associated with systemic inflammation. This was primarily attributed to the species Alatina alata, whose occurrence patterns correlate with the seasons and the lunar cycle. Although patients presented with slightly less severe symptoms than those observed in Australian studies, one case of cardiac decompensation—the first reported outside the Pacific—was noted.