It stays effective for one full month and keeps pests away from my pet.
My kitty is prone to worm infestation so I use this spot on because of its immediate action. Helps prevent ticks and flea infestation too.
It works great on cats. All three of my felines got completely cured.
didn't expect that it will work so fast but it did. would recommend
A product that does what it says on the pack. Never once had a problem after using it.