Hemolysin is a biological toxin that lyses or destroys red blood cells. There are several synonyms for this word that can be used interchangeably, including erythrolysin, cytotoxin, and heptolysin. Erythrolysin refers to toxins that specifically target red blood cells, while cytotoxin is a broad term that encompasses any substance that is toxic to cells. Heptolysin specifically targets liver cells, but can also refer to a hemolysin that targets other organs as well. Other related terms include hemolysis, which is the process of breaking down red blood cells, and hemolytic anemia, which is a condition where red blood cells are destroyed at a faster rate than they can be produced.