Dr. Clark books state that you can get quite ill from the Liver Cleanse if you don't kill the parasites first, which you can assume are in there. The parasite cleanse is only 2 1/2 weeks, or you could buy the Zapper and Zap every day for 1 week instead! I personally find that the Zapper gets rid of many other problems also and highly recommend it! Hang in there as it takes several Liver Cleanses to clear you out!