I recently did an herbal detox and yes, it was stressful on my body, however I feel as if I am healthier as a result. Some days it felt as if my cerebellum was tinsel, and on at least one night my dreams were kinetic. Very rare thing with me so probably no co-incidence as it was probably the most intense kinetic dream ever. I felt mild seizures across my face as well.
Basically some of the ingredients are considered toxic in high doses. The main ingredients of the whole concoction were, wormwood, black walnut hull, and cloves, along with a good handful of other herbs. Got it from kaicollection on ebay.
I'd say yeah, some herbal detoxes do work. Now I am onto an intestinal cleanse.