Clinical Trials 101

Curious about clinical trials? Start here to learn what they are, how they work, and who’s involved.

What is a clinical trial?

A clinical trial is a research study that involves people. It usually tests a medicine, medical device, or other treatment to see if it is safe and works well for a disease. It may also be called a “clinical study” or an “interventional clinical trial.”

Is a clinical trial a treatment?

A clinical trial is a type of science experiment. It is not the same as regular medical treatment. If you join a clinical trial, there is no promise that it will help you. Any medicine or treatment you get in the trial is still being tested. This means doctors don’t know yet if it will work. But by joining a trial, you are helping scientists learn more—and that could help you and other patients in the future.

Learn more about clinical trials with this video from the Center for Information and Study on Clinical Research Participation (CISCRP).

Clinical trials are conducted in phases

Phase 1:

  • This is usually the first time the medicine is tested in people
  • Researchers see how the medicine acts in the body
  • They try to find the best dose to use

Phase 2:

  • Researchers start to see how well the medicine works
  • The medicine is often compared to a placebo (a fake treatment) or other treatments

Phase 3:

  • Researchers get more information on how well the medicine works
  • It is always compared to a placebo or other treatments
  • This is the final step before asking for approval to use the medicine

Phase 4:

  • The medicine is studied even after it’s approved
  • Researchers keep checking its safety and how well it works over time

What is a placebo?

A placebo is a fake version of a medicine. It looks the same as the real one, but it doesn’t have any ingredients that treat the disease. Researchers compare what happens with the placebo to what happens with the real medicine. This helps them see if the medicine works.

Who is involved in clinical trials and what do they do?

Many people and organizations work together to run a clinical trial:

  • Study participants are the people who volunteer to take part. They may have a medical condition or be healthy.
  • Friends and family support participants by asking questions, helping with transportation, and offering emotional support.
  • The study doctor leads the trial and follows a detailed plan called the study protocol.
  • Study coordinators, nurses, and staff help with the day-to-day activities of the trial.
  • Pharmaceutical companies, government agencies, foundations, and universities often fund the trial, hire the study team, and check that everything is going as planned.
  • Ethical review boards and regulatory agencies (like the FDA in the U.S. and EMA in Europe) help protect participants by making sure the trial is safe, fair, and follows the rules. They also review the data to decide if the new medicine can be approved.

Learn more about everyone involved and their roles with this video from the Center for Information and Study on Clinical Research Participation (CISCRP).