Podophyllotoxin is derived from the roots of podophyllum plant. It is applied directly to genital warts. When it penetrates the wart tissue, it has a toxic effect on the nuclei of the wart cells. The nucleus is the cell's control centre. It controls cell division and multiplication (mitosis). This results in the healthy growth of tissue. Podophyllotoxin is an antimitotic and by its action on the nuclei, prevents the wart cells from dividing. This stops the cells multiplying. Over time, all the wart cells die and new healthy tissue grows in their place.