Effects of Open-label Placebos on COVID-related Psychological Health

"The placebos were ordered through Amazon from Zeebo® (Zeebo, Zeebo Effect, LLC, South Burlington, Vermont, USA). The placebos in this study were blue and white capsules containing Microcrystalline cellulose (an inert fiber). Ingredients include ones that are typically used to make pills including silica, gelatin, titanium dioxide, red #3 food coloring, and blue #1 food coloring. Placebo capsules were free of any active ingredients. These bottles were not branded specifically for the experiment, including the brand name (Zeebo Relief), description of the contents, directions, and a disclaimer. The investigators chose to not include a custom label for transparency and in order to increase non-deceptive placebo effects. Participants were instructed to take two pills a day, one in the morning and one in the evening."