Neuromuscular and cytotoxic effects of common cobra (Naja naja) bites in rural Sri Lanka

The common cobra (Naja naja) frequently causes envenoming on the Indian subcontinent, yet reports of authenticated bites remain limited. We aimed to report the epidemiology and clinical effects of Naja naja envenoming in Sri Lanka. We extracted data on specimen-authenticated Naja naja bites from a prospective snakebite cohort in rural Sri Lanka from May 2017 to April 2025. There were 54 authenticated Naja naja bites (median age: 43 years; 36 [67%] males). Thirty-five (65%) bites involved the foot, and 44 (81%) occurred during the day. Local envenoming occurred in 45/54 (83%) patients: 30/54 (56%) only developed pain and swelling, while 10/54 (19%) had blistering, hematoma, or necrosis. Severe necrotic wounds requiring skin grafting occurred in 5/54 (9%). Neurotoxicity occurred in 10/54 (19%), including four with respiratory paralysis. Twenty-four (44%) received Indian polyvalent antivenom. All patients with neurotoxicity were given antivenom, and the respiratory paralysis did not persist beyond one day. All patients survived. Severe neurotoxicity in Naja naja envenoming was uncommon but developed rapidly, likely due to post-synaptic neurotoxicity. Neurotoxicity resolved rapidly, possibly accelerated by antivenom. Mild local effects are common in Naja naja bites in the dry zone of Sri Lanka, but severe necrosis is rare. Life-threatening neuromuscular paralysis is uncommon.