Placebos

Placebos are inert substances or sham procedures designed to resemble active medical treatments but lack therapeutic properties. In clinical research, placebos serve as controls to measure the true effects of new interventions. Placebo-controlled trials usually randomize participants and blind patients and researchers to treatment allocation to minimize bias.

The placebo effect refers to clinical improvements that arise after receiving a placebo, driven by expectations, conditioning, and the patient–provider relationship. Placebos can influence subjective symptoms such as pain, sleep, and mood, and may modestly affect certain objective measures. The magnitude of the placebo response varies by condition, study design, and patient characteristics.

Placebos may be simple inert pills or more complex sham procedures that imitate real treatments. Open-label placebos, in which participants are told they are receiving a placebo, have shown effects in some studies, suggesting care context and expectations can contribute to outcomes.

Ethical considerations focus on deception, informed consent, and transparency. Blinding often requires concealing treatment allocation, which raises ethical concerns, especially in non-trial care. Researchers are exploring ethical use of placebos and the potential of open-label placebos in certain settings.

Placebo use highlights the importance of rigorous trial design and ethical standards, while recognizing that patient expectations can influence health outcomes. Placebo research continues to clarify mechanisms and boundaries of the placebo response, including neurobiological pathways and psychosocial factors.