many drugs used for parasites are used FIRST in animals .. then once proven safe enough are administered to humans. For instance, IVOMEC... a prep for livestock is the only IV prep for ivermectin is being used as "salvage therapy" in humans for strongyloidiasis ( due to complications of paralytic ileus that commonly occurs with oral meds in this case... ie ... it SAVES their lives , when nothing else works. Fenbendazole is same class of drug as mebendazole and albendazole. The things you have to note are the differesnt half lives etc... because thats what counts. HOW LONG will this drug stay in your system killing parasites. Albendazole is a GREAT drug because it targets cestodes nematodes and to some degree trematodes with a long half life of 16 hours. This business of killing parasites is serious ... sometimes LIFE THREATENING pursuit. To treat them insufficiently is worse than doin nothing at all. If you treat them inconsistently or incompletely they will will come back even worse. You kill the mommy to get a thousand babies etc... Good thing about herbs is that they kill more slowly, therefore placing less burden on the body at a given time, where as drugs are like atomic bombs... ready or not here come the million larvae... and sometimes septic shock .. and occasionally death. Which is why some parasitologists maintain that herbs merely dessiminate the parasite ... ultimately conpounding the problem and make it that much more dangerous and difficult to treat. These are things we all have to decide for ourselves. The risks we are willing to take.