You take the Humaworm for 30 days and then you wait 90 days and then you take the Humaworm again for another 30 days then wait 90 days and so on until you are clean. You will know when you are getting clean if you research your bm with a chopstick. Some of the heavier critters sink to the bottom and if you are infected with roundworms (ascaris) they live in the bm so you can't see them unless you research. Hope this helps. Donna