I've heard of cayenne pepper, but I have never used it. I do not worm my chickens; I do have a fecal done every so often, and it has never come back as them having a "load" of worms, so I have not wormed.
My avian vet, however, has always recommended that I work with
Ivermectin Eprinex (cattle wormer) once each 6 months. As I stated, I do not, as I've never had a heavy load. I personally don't know as I'd trust cayenne for a known heavy worm load, however. Perhaps the Eprinex as a one-time thing to make SURE you get rid of them all, and then maintenance each 6 months with Cayenne? I think that's probably what I'd opt to do, if I had a known heavy worm load.