Hi Gretchen – let first say that everyone is different, and you should check with your doctor before taking any new medication. That said, my wife and I do take a 6-month preventative for parasites. It is a two-day treatment, one pill the first day, and two of a different type the second day. Has it helped? Well, it’s one of those things where you can’t prove a negative – we have not been bothered by parasites in the three years we have lived in Salinas, but I cannot say it is because of the medication. For example, we also take the precaution of drinking bottled water, and washing our fresh fruits and vegetables in an mild antibiotic solution.