A clinical trial is a research study designed to answer specific questions about new therapies, diagnostic tests, screenings, and disease prevention by testing new procedures in people. Clinical trials (also called medical research and research studies) are used to determine whether new drugs or treatments are both safe and effective. Carefully conducted clinical trials are the fastest and safest way to find treatments that work.

Ideas for clinical trials usually come from researchers. Once researchers test new therapies or procedures in the laboratory and get promising results, they begin planning trials to test the therapy in people. New therapies are tested on people only after laboratory and animal studies show promising results.