Merely Possessing a Placebo Analgesic Improves Analgesia Similar to Using the Placebo Analgesic

Background
Placebo analgesia studies generally reported that the actual use of a placebo analgesic reduces pain. Yeung, Geers and Kam (2019) found that the mere possession (without use) of a placebo analgesic also reduces pain.

Purpose
We investigated the relative effectiveness of using versus possessing a placebo analgesic on pain outcomes.

Methods
In Study 1a, 120 healthy adults were randomized to either the experimental (EXP) conditions (EXP1: used a placebo analgesic cream, EXP2: possessed a placebo analgesic cream) or control (CO) conditions (CO1: possessed a sham cream, CO2: no cream). All participants underwent a cold pressor test (CPT). Study 1b further delineated the effect of possession from the effect of use. Sixty healthy adults were randomized to either the placebo-possession condition (merely possessed a placebo analgesic cream) or the placebo-possession-use condition (possessed and used a placebo analgesic cream). All participants did a CPT.

Results
In Study 1a, as expected, a placebo effect was found—participants who used a placebo analgesic cream showed better pain outcomes than the two CO groups. Surprisingly, participants who merely possessed a placebo analgesic cream performed equally well as those who actually used it. In Study 1b, participants in the two conditions did not differ in most pain outcomes. Participants who possessed and used a placebo analgesic cream only showed slightly more reduction in pain intensity compared to participants who merely possessed the placebo analgesic cream.

Conclusions
Our results suggest that merely possessing a placebo analgesic could enhance pain outcomes similar to that of applying the placebo analgesic.