How long does frontline work?

Frontline typically works for between 12 and 30 hrs after application for cats, depending on your pet’s activity levels, and up to three days with dogs, provided they do not become immersed in water or bathed. However, this may vary depending on the individual animal and the environmental conditions. If your pet swims or gets wet frequently, you may need to reapply Frontline® more often.

As long as you don't bathe (or allow your dog to) or get a lot of rain, FRONTLINE Plus for Dogs will keep killing 100% of re-infesting ticks for months. Frontline can remain effective through a single shampoo in both Dogs and Cats and through two shampoos in Dogs only.