I'm not sure, I believe I am having problems with parasites in my Sinuses, and how far beyond that they go, I don't know. I have to assume that they do. It sure seems like it's difficult to eliminate anything from the head area because they just come back. I guess once they migrate to a certain area it's hard to get rid of them. And remember the Zapper current can sometimes go around certain things (like the eyeball for instance) that's why it's important to do an internal parasite cleanse as well.