A placebo is an inactive harmless agent used for testing against the active drug. The results of the active compound are compared with the placebo to better understand the actions of the active drug. Often the participant, the physician and the study coordinator are not told which group is getting the actual drug, and which is receiving the placebo. This method is used as a way to prevent bias on the part of the patient and the doctor. The patient makes this decision.
Informed consent is required for participation in all clinical studies involving human subjects.
Individuals are given information about what is involved in the study, including possible benefits and risks. Questions are encouraged by the physician or study coordinator. After this information is presented, individuals can make a decision whether or not to participate. The individuals' consent to participate is then documented in their medical history. Mayo Foundation for Medical Education and Research.