Expected response to antivenom

Response to antivenom is often difficult to assess. Recovery is determined by reversibility of the venom’s effects, and the time taken for the body to recover once venom is neutralised. Most systemic envenoming effects (eg VICC, neurotoxicity and myotoxicity) are irreversible, and antivenom only prevents their occurrence if given early. Clotting times in patients with VICC will only normalise once clotting factors are resynthesised by the liver (over days).

Compounding this problem, many biomarkers of systemic envenoming (eg serum creatine kinase concentration for myotoxicity, serum creatinine concentration for acute kidney injury) have delayed increases, so they may remain high or even rise after antivenom, despite the body recovering.

Other nonspecific systemic symptoms of envenoming (eg nausea, vomiting, headache, diarrhoea, abdominal pain) and anticoagulant coagulopathy are potentially reversible with antivenom.