humaworm
Different people react in different ways to their initial parasite cleanse. It depends on the general health of the person before the cleanse and it also depends on what type of parasite infection they have. Generally, the more severe the infection, the more severe the die-off.
I don't know too much about the Parastroy formula, but it might not have enough supporting herbs to lessen the die-off effects. Your bowels DO need to be in reasonably good working order so that the parasites and toxins are removed very quickly (this is why HUMAWORM contains 8 bowel helping herbs).