The subtle central effect of nutraceuticals: Is it placebo or nocebo?

Herbal medicines are often perceived by the general public as a “soft” alternative to Western Medicine, but the use of these substances can be risky since they can induce nocebo effect [1]. In 1961 Walter Kennedy chosen the term nocebo (Latin for I will harm) as the counterpart of placebo [2]. This term was introduced a few years after Henry Beecher published his paper on the placebo effect [3]. Most clinical studies explored the beneficial effects of nutraceuticals and ignored their nocebo effects, The seeds/oil of Nigella sativa has anti-inflammatory, analgesic, antipyretic, antimicrobial, hypotensive, hypoglycemic, antiepileptic and antineoplastic activity [4-7].