What is a Clinical Trial?

Medical advancements are made possible through volunteer participation in clinical research.

Clinical trials help determine if a new treatment is safe and effective for humans. Study participants aid researchers in learning more about disease management and prevention to improve the health of people now and in future generations.

Clinical trials are conducted in the following four phases and help researchers answer questions as the study progresses to enable discovery of new drugs, new surgical procedures, new medical devices, new treatment protocols, and new ways to improve the quality of life for people with acute or chronic illnesses:

Phase I

Small Group

Testing the new agent for safety and proper dosing and treatment to give with a small number of participants, typically less than 50.

 

A female nurse wearing a stethoscope is hugging a young, smiling patient.

Phase II

Wider Group

Testing the new agent for efficacy (how well it works in treating the target disease) and for possible side effects. Typically, 100 or fewer participants are enrolled.

A nurse wearing a face mask is measuring the temperature of a young female wearing a mask. People wearing masks are waiting in line.

Phase III

Large-scale Group

A large-scale trial phase (typically a few hundred to a few thousand participants) to measure efficacy and effectiveness, often compared to existing approved therapies.

A male scientist is writing on a tablet. A microscope is nearby.

Phase IV

Long-term Monitoring

Monitoring long-term side effects after the approval of the new therapy.

A female and male scientist are working on their computers in a scientific lab.