Strange facts about ‘placebo’

You can tell someone you are giving them a placebo and it will still work (‘open label placebo’).
‘Placebo’ can be deliberately manipulated to be stronger or weaker (e.g. a warm, confident doctor beats an uncertain, absent doctor for IBS — see Kaptchuk 2008).
The size of placebo effects differs over time in a single trial. Tuttle et al. (2015) found the placebo effect grew in effectiveness over the length