R.I.P. Fleas Extra contains permethrin which is toxic to cats. Even though R.I.P. Fleas Extra contains a relatively low concentration of permethrin it is recommended to remove all cats and kittens from the room being sprayed. Immediately after spraying, open windows and ventilate the room for at least 1 hour. Make sure all spray mist has settled and all surfaces are dry before allowing cats and kittens to re-enter the room. It is important you allow your cat free access to all rooms in the house after this period of ventilation, as the presence of your cat will provide a stimulus for pupae to hatch.