Placebos are harmless, but they work, posing problems for medicine.
D035843:Biomedical Research; D008192:Deception; D005069:Evaluation Studies as Topic; D006801:Humans; D009369:Neoplasms; D010146:Pain; D005791:Patient Care; D004364:Pharmaceutical Preparations; D010919:Placebos; D012106:Research