An experimental study in distinguishing an authentic herbal substance from sham herbal substances.

Objectives: An unblinded randomised trial can result in biased treatment effect estimates and lead to erroneous conclusions on the efficacy of the therapeutic intervention. Unlike pharmaceutical substances, Chinese herbal medicines have special characteristics including texture, colour, odour and taste as the origin of these constituents are different. In addition, its distinctive odour makes blinding of Chinese herbal medicine RCTs very difficult, as the placebo substance needs to match the special characteristics of the herbal substance being investigated.