The analgesics morphine and tramadol do not alter the acute toxicity induced by Bothrops asper snake venom in mice.

Highlights: [•] Analgesics tramadol and morphine were used in mice injected with Bothrops asper venom. [•] Analgesics did not alter the acute toxicity of B. asper venom in mice. [•] Precautionary (prophylactic) analgesia should be introduced routinely in Toxinology. [Copyright &y& Elsevier]