Credelio is the new treatment for fleas and ticks. The active ingredient is Lotilaner, a fast-acting killer of fleas and ticks. It is given as a tablet and seems the most efficient and easy way to control these two important parasites and prevent the spread of more nasty diseases which ticks carry. We really think this is the future of flea control. There is evidence that Credelio kills numerous other external parasites common in cats and dogs.