Anaphylaxis to antivenom in the background of alpha-gal syndrome ‒ a case report

Introduction and aim. Alpha-gal syndrome is an IgE-mediated allergy to galactose-α-1,3-galactose, typically associated with delayed hypersensitivity reactions following ingestion of mammalian meat. Severe immediate hypersensitivity reactions to equine-derived antivenom in patients with previously unrecognized alpha-gal syndrome are rarely reported. We report one of the first cases from South Asia of refractory anaphylaxis following equine-derived antivenom in a patient with previously undiagnosed alpha-gal syndrome, highlighting an important but under-recognized clinical challenge. Description of the case. A 45-year-old Sri Lankan woman developed refractory anaphylaxis shortly after administration of equine-derived antivenom for a Russell’s viper bite. She required intravenous adrenaline and noradrenaline infusions, fluid resuscitation, and high-dependency care, with subsequent full recovery. Further evaluation revealed a history suggestive of alpha-gal syndrome, including recurrent urticaria and wheezing following consumption of mammalian meat and dairy products, as well as possible anaphylaxis to wasp stings. Serum alpha-gal–specific IgE levels were markedly elevated. Conclusion. This case highlights the potential for severe hypersensitivity reactions to mammalian-derived antivenoms in patients with alpha-gal syndrome.