Drug addicts use sometimes drugs through their anus since the absorption is faster. So you are absorbing caffeine in a faster rate which can be harming, we know that caffeine is a type of drug that can cause some problems depending of the quantity, specially to the kidneys. Well at least this enema isn't something very popular and I think humanity is safe... there are many weird stuff that people used in the pass and for sure they don't use it anymore because it caused more harm than good.