Kill Fleas Fast using Frontline Spot On For Cats. The UK's number 1 flea treatment for Cats. Non systemic spot-on, acts on contact not via your pet's blood. Effective even after bathing from 48 hours after treatment. Kills 98-100% of fleas within 24 hours for approximately 2 months. Kills ticks within 48 hours for up to 1 month. Fully controls infestations of lice within 48 hours.