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

The common cobra (<i>Naja naja</i>) frequently causes envenoming on the Indian subcontinent, yet reports of authenticated bites remain limited. We aimed to report the epidemiology and clinical effects of <i>Naja naja</i> envenoming in Sri Lanka. We extracted data on specimen-authenticated <i>Naja naja</i> bites from a prospective snakebite cohort in rural Sri Lanka from May 2017 to April 2025. There were 54 authenticated <i>Naja naja</i> 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 <i>Naja naja</i> 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 <i>Naja naja</i> bites in the dry zone of Sri Lanka, but severe necrosis is rare. Life-threatening neuromuscular paralysis is uncommon.