Constipation can be a problem with any of the high fiber cleanses...but it seems to be less of a problem with HH. HH contains dandelion in the bulking agent and also the intestinal cleansing tabs...and dandelion stimulates bile flow...which is a natural laxative that your body produces. I always suggest that folks be prepared to do enemas or colonics during any of the cleanses...just makes it easier and prevents this problem! Weekly colonics should be fine...but you can also do enemas at home (use purified or distilled water) in addition...if you need them.
No...coffee is not a laxative or irritant. Since it is a stimulant it does help jump start the system for some folks. BUT...it is also a diuretic...so it can contribute to dehydration if you don't drink enough water.