Russell's viper venom contains an enzyme that activates factor X, one of the proteins in the coagulation cascade, bypassing the earlier steps that most clotting tests depend on. Purified and standardised, that fraction became the basis of the dilute Russell's viper venom time, a routine assay used to screen for lupus anticoagulant in patients with unexplained clotting problems.
In a bite, the same chemistry is destructive. The venom consumes clotting factors until the blood loses the ability to clot at all, producing persistent bleeding, and it damages kidney tissue and small blood vessels. Acute kidney injury and pituitary damage are recognised late complications in survivors.
The species is also a public health problem for a reason unrelated to potency: it does well in farmland. Rodents follow crops, the viper follows rodents, and barefoot agricultural work at dusk puts people and snake in the same place. It is counted among the four species responsible for the bulk of snakebite deaths in India.