Authors: AbdulRahman AlMirza , Amal Almakhmari , Ali Albalushi , Hassan I. Al Balushi

Abstract

Background: Sea snake bites are uncommon but potentially life-threatening emergencies due to the neurotoxic and myotoxic effects of their venom. Antivenom remains the mainstay of treatment; however, it may rarely cause severe hypersensitivity reactions, including anaphylaxis.

Case Presentation: A 34-year-old previously healthy male presented to the emergency department in Oman 1.5 hours after a confirmed sea snake bite sustained while fishing. Initial examination revealed a fang mark on the right foot without significant local swelling. Shortly after initiation of intravenous antivenom, the patient developed vomiting, lethargy, hypotension, oxygen desaturation, and a generalized tonic-clonic seizure. Antivenom administration was immediately discontinued, and the patient was treated with intramuscular epinephrine, intravenous hydrocortisone, fluid resuscitation, and supportive care. The seizure resolved promptly, and he recovered without neurological sequelae. Laboratory investigations demonstrated mild leukocytosis and a transient rise in creatine kinase levels. Computed tomography of the brain was unremarkable. The temporal relationship to antivenom infusion, associated hemodynamic instability, and rapid response to epinephrine strongly suggested probable antivenom-induced anaphylaxis as the underlying mechanism.

Conclusion: This case highlights a rare presentation of probable antivenom-induced anaphylaxis manifesting as seizure following sea snake envenomation. Close monitoring during antivenom administration, prompt recognition of anaphylaxis, and immediate availability of resuscitative measures are essential to optimize patient safety.

Keywords: Anaphylaxis, antivenom, emergency medicine, hydrophiinae, pyrogenic reaction, sea snake, seizure.