FIPROtec Combo spot-on solution for cats contains Fipronil & the insect growth regulator S-methoprene. These ingredients not only kill adult fleas, ticks & biting lice but also impedes on the flea life cycle. This results in the prevention of any exposed eggs and/or larvae from developing in your home for up to 6 weeks.• Kills adult fleas for up to 4 weeks.• Kills ticks for up to 2 weeks.• Effective against fleas, ticks & biting lice.• Prevents eggs laid by exposed fleas from developing for up to 6 weeks.