I have done the HUMAWORM program for many years. Twice per year every year as a child and as an adult. The only side effect is a slight heartburn feeling for a few minutes after taking the capsules. This is due to the release of the herbs. You will have more bowel movements but there is no cramping because of the high amount of cramp bark in the HUMAWORM formula. My grandparents "wormed" my parents and my parents "wormed" my siblings and me. I can tell you this. I've never had a yeast infection nor have any of us had any major health problems. We've just always been a healthy bunch of folks. My grandmother died just last year at 98 years of age and up until the day she died, she lived alone, drove and wore high heels to church! Her heart just conked out, no disease, just heart failure. I truly attest this to bi-annual "worming".