Revolution uses selamectin as its active, applied monthly for fleas, ear mites and some intestinal nematodes. Advocate combines imidacloprid and moxidectin in a monthly spot-on, covering fleas, ear mites and several nematodes, and used for heartworm prevention.

Indoor cats needing one routine that addresses external parasites and some internal ones fit these drops. Both come in weight bands, so the right range must be chosen, applied to skin at the back of the neck rather than fur, and timed around bathing.

Different spectra mean the two are not simply interchangeable: heartworm prevention and tapeworm coverage must be defined first. In multi-cat homes, drops carry a licking risk, so separate cats until dry, and record any short-term local reaction.

Confirm local parasite risk and the cat's weight, then let a vet choose the active and the pack size. Prescriptions and doses should not be copied from forums, especially for kittens, pregnant cats and sick cats. No deworming plan replaces vaccination and check-ups.