A placebo is anything that looks like a real medical treatment but is not, in reality. Placebos are medical substances that improve the health status of the person due to the patient's belief that the substance is indeed effective. The opposite of the placebo effect is the nocebo effect. A nocebo is a medical substance with no medical effects that worsens the health status of the person due to the patient's negative beliefs and expectations. In psychiatry, the placebo effect plays a significant role in the majority of mental disorders, including depression, anxiety, addictions, and schizophrenia. A few prominent symptoms of nocebo effect are nausea, itching, bloating and sleeping issues. This book is a compilation of the works of various international experts carrying out research with respect to placebos and nocebo, and their significance in clinical psychiatry. It is a vital tool for all researching or studying placebo and nocebo effects.