A clinical trial is a research study that uses people to find new ways to improve health. People volunteer to be in clinical trials. Clinical trials can:
- Test new treatments to see if they help with certain diseases or conditions better than the current treatments
- Test treatments or lifestyle changes to see if they prevent or lower the chance of getting certain diseases
- Test new ways of finding out if people have certain diseases
Clinical trials that test new treatments, such as medicines, fall into one of three types. The type of trial depends on its goal and how much testing the treatment has already had. There are three different types of treatment trials:
- Phase 1 (I) trials – In phase I trials, doctors check the safety of a new treatment. They learn how the medicine should be given, how often it should be given, what dose is safe and what the side effects are.
- Phase 2 (II) trials – In phase II trials, doctors give a new treatment to a group of people with a certain disease. The doctors check the treatment's side effects and how well it works to treat the disease.
- Phase 3 (III) trials – In phase III trials, doctors compare a new treatment with the current treatment for a certain disease. They learn if the new treatment helps the disease better, worse or the same as the current treatment. They also learn if the new treatment has more or fewer side effects than the current treatment.