I haven't started using my latest purchase of Paratox, but based on past usages going back over 20 years, it works. It does so without poisoning your pet along with the parasite organism. My last use was to clear giardia from a rescued kitten. Conventional methods weren't working and the vets wanted me to give him an even stronger, and thus more toxic, antiparasitic. Paratox did the trick and kept the giardia out of my other 2 kitties. I should have ordered it first thing.
About 4 years ago my dog developed some skin problems that the regular vet couldn't figure out. I also developed a similar problem. At the time I was using hay as mulch for my vegetable garden. Ferrel cats began pooping in the hay. My dog ate the poop several times. Resulting in our skin rashes. I was pretty sure it was some kind of parasite from the cats, but the vet had no way of telling. After a lot of research online, I discovered Paratox. I used it as recommended and my dog's skin recovered completely. I now use it regularly. About once a year.
After the success with my dog I used it for myself even though it is not recommended for human use. I didn't find any other option. The rashy eruptions on my skin also went away.
In the meantime I stopped using hay as mulch and found other ways to keep the ferrel cats out of my vegetables.