In East Asian countries, even after western medicine’s addition to the system, traditional medicine is still routinely used [34, 35]. As a result, acupuncture is easily accessible and embedded in cultural background. Therefore, participants as well as the researchers of acupuncture trials are assumed to be more familiar with acupuncture compared to those in non-Asia region . This brings concern to Asian researchers that the study participants will easily distinguish real from placebo acupuncture. The rationale behind such fear is not simple, as studies examining the influence of the participant’s previous experience on detecting placebo acupuncture presented conflicting results [37, 38]. The notion that blinding may be hampered if trial participants are fully informed on details of placebo acupuncture, is partly explained in our BI analysis. While 21% of the participants in the placebo acupuncture group from DD/MI category made incorrect guesses beyond chance, i.e. they believed they received real acupuncture, 16% of those in the placebo acupuncture group from FD category made such guesses. It could be interpreted that though not statistically significant, the participants on the placebo acupuncture arm who were not very well informed about placebo acupuncture tended to guess that they received real acupuncture more than participants in FD category did. It reflects participants’ wishful thinking, which may lead to an augmented placebo effect . This finding is in line with the result from the Cochrane review of all placebo interventions where a higher placebo effect was reported in trials without correct information of placebo than those with correct information . An altered placebo labeling study also has shown that placebo effect goes higher as the label on placebo changes from placebo, uncertain to valid medicine . Given our BI analysis and the results from other relevant studies, the hypothesis can be generated that full disclosure of placebo in PILs may undermine successful blinding of participants and this should be systematically evaluated in the future studies.