One of curcumin’s greatest disadvantages is that it is poorly absorbed when orally ingested by itself.[1]
Dosages of up to 8 grams per day of curcuminoids have not been associated with serious adverse effects in humans.[2] However, comprehensive long-term studies are needed to confirm this lack of adverse effects. Studies using high doses of curcumin have reported some mild adverse effects, including nausea, diarrhea, headache, skin rash, and yellow stool.[3][4][5] Use of curcumin with piperine (a black pepper extract) may increase adverse reactions to curcumin, because piperine greatly increases intestinal permeability.[6] Not all formulations of curcumin have been safety tested to the same degree.