Nephrotoxins are proteins that impair renal function. Most venom nephrotoxins are found in snakes, but some are also described in spiders and sea anemones. Common renal manifestations are acute renal failure (ARF) , proteinuria, hematuria and pigmenturia.

ARF can involve both direct and indirect nephrotoxic actions. Direct action is observed in patients a few hours after snakebite without hypotension, hemorrhage, intravascular hemolysis or rhabdomyolysis. It can also be deduced from in vitro experiments (Mandal and Bhattacharyya, 2007). Venomous snakes have enzymes that can cause direct nephrotoxicity; metalloproteases can cause proteolysis of the extracellular matrix and disrupts cell-matrix and cellular adhesion, whereas phospholipases A2 can cause membrane injury and tubular necrosis (Sitprija, 2006).
Indirect ARF is a consequence of rhabdomyolysis, intravascular hemolysis, disseminated intravascular coagulation (DIC) or hemorrhage that is caused by myotoxins or hemotoxins (Sitprija, 2006).

A restricted number of toxins have been described with nephrotoxic activities. Due to this small number, no UniProtKB/Swiss-Prot keyword describing this activity has been created.