Try dosing yourself several times in a row, every two weeks, like clockwork. The medicine does not kill the eggs and the life cycle of threadworms is 5-6 weeks. You must wait for the eggs to hatch out, but if you wait too long the babies will reach juvenile stage, lay more eggs and start the whole cycle over again. Wash your anal sphincter really good every morning. They lay their eggs there at night. Wash all your clothes, bedclothes, and bed linens when you dose yourself, otherwise eggs will linger in the linens and reinfect you. Eggs can live up to two weeks in clothes and on sheets. This is what I've heard, but I don't know anything for sure: You cannot take the medicine continuously because the eggs will not hatch out while there is medicine in your body. It can take as long as 10 months to get rid of parasites if you have a heavy load. Once you've got them, you are susceptible to reinfection, so periodic routine maintenence is advisable.** I would recommend that you take a natural herbal formula to exterminate, and a homeopathic remedy to strengthen your immune system, instead of using pharmaceuticals. Drugs are too harsh for long term use.