About Clinical Trials

Only you can decide if a clinical trial is right for you

Clinical trials need people of both genders, all racial backgrounds, and all ages. Some trials involve people with a disease or condition; some require "healthy volunteers" (people who do not have a particular disease).

Past study participants have helped to develop important medical milestones such as vaccines, ultrasound, x-ray equipment, tools to stop smoking, and new medications to treat many common conditions such as asthma, diabetes, and cancer.

Talk to your health care provider to see if there is an appropriate study for you. Each trial has a set of eligibility criteria that participants need to meet such as age, gender, and medical history.

Points to remember

If you are thinking about participating in a clinical trial, please remember that:

  • The study may or may not help you personally; the results of the trial may help others in the future that have a health problem.
  • Being part of a study is completely voluntary. You can withdraw at any time. Your doctors and your research team will support whatever you decide.
  • Your routine medical care will not be impacted by participating in a study. Even if you withdraw, your ongoing care will remain the same.
  • There are always risks involved with clinical trials. We study a new treatment or medical approach because it has shown strong promise in laboratory and animal studies. Results in humans may be different, though. The new treatment may not be better than the standard therapy, or it may have unexpected or more difficult side effects.
  • If the study is comparing different treatments, participants cannot choose which one they receive because they are randomly assigned to one treatment or the other.

Types of trials

Our trials fall into the following categories.

  • Treatment trials: Treatment trials test new ways to treat diseases or conditions. They might include new drugs, devices, combinations of drugs, or therapies like surgery. A treatment trial may also study "off-label" uses for an existing FDA-approved treatment. Off-label means the drug is being tested as a treatment for a different condition than the drug was originally designed and approved to treat.
  • Prevention trials: Prevention trials test ways to prevent disease. Methods of prevention may include lifestyle changes, vaccines, or vitamins.
  • Screening trials: Screening trials test for the best ways to detect diseases and conditions. These trials involve participants who have no symptoms of the condition.
  • Diagnostic trials: Diagnostic trials test for the best ways to diagnose diseases and conditions, and usually involve people who already have signs of these conditions.

Phases of a clinical trial

The U.S. Food and Drug Administration (FDA) requires at least three phases before a new medication can be approved.

Phase I trial

In a Phase I trial, an experimental drug, device, or treatment is tested on a small group of people, usually with 20 to 80 participants. The purpose of a Phase I trial is to determine the safety of the treatment, device, or drug. This phase may be called nonblinded (or "open-label"), because both researchers and volunteers know what medication is being used.

Phase II trial

In a Phase II trial, further study of a new drug, device, or treatment with 100 to 300 participants takes place with participants who have the condition or disease for the target of the treatment. A Phase II study of an investigational treatment is designed to determine if the drug or device is an effective treatment for a specific disease, has any side effects, or has any risks.

Phase III trial

In a Phase III trial, large groups of people (1,000 to 3,000) participate to allow researchers to collect data on safety and efficacy of a drug or treatment and to compare the new treatment to the standard treatment or to placebo (an inactive treatment used to compare the effects of the experimental treatment with no treatment). This phase may be randomized and blinded. In a randomized study, participants in the trial are assigned randomly (like flipping a coin, for example) to the groups with the new treatment, standard treatment, or placebo, when relevant. A blinded study means patients and/or doctors do not know which treatment they are receiving (single-blinded and/or double-blinded).

Phase IV trial

In a Phase IV trial, further study takes place to determine the risks, benefits, and best use of the drug or treatment once the treatment is being marketed. Usually thousands of people are involved in this phase.

To learn more about clinical trials in general, visit clinicaltrials.gov.