Clinical Trials: FAQ


Question: What is a clinical trial?

Answer: A group of people voluntarily agree to participate in a specific medical experiment by researchers. This can range from testing new prescription drugs to medical devices to procedures.

Q: How does a clinical trial work?

A: Clinical trials compare new medical approaches to a standard approach or to a placebo, which has no active elements (such as a sugar or water pill) and acts as a constant for comparison. The goal of a clinical trial is to determine the effectiveness of the new approach when compared to standard care and/or current practices.

Q: Why are clinical trials important?

A: Clinical trials are meant to increase knowledge and improve treatment, diagnosis, and prevention of diseases and conditions. One of the most important purposes of a clinical trial is to ensure the new drug or approach is safe and beneficial before selling it on the public market.

Q: Who conducts a clinical trial?

A: Clinical trials have a lead investigator and a research team comprised of health care professionals, such as doctors, nurses, and social workers. They are often sponsored or funded by pharmaceutical companies, academic medical centers, federal organizations, health groups, and other organizations or even individuals.

Q: Where do clinical trials happen?

A: Location varies by trial, but many are conducted at hospitals, universities, doctors’ offices, and clinics.

Q: How long does a clinical trial take?

A: Duration varies by trial. Some last a few months and others can last years, depending on which phase the trial is in, the type of experiment, and what the trial entails. Participants are informed of the duration before joining the trial.

Q: What are the phases of a clinical trial?

A: Clinical trials are one part of the clinical research process as defined by the U.S. Food and Drug Administration (FDA). There are four phases when testing a new prescription drug in a clinical trial.

Phase 1 – tests on 20 to 100 healthy participants over several months to monitor safety and dosage

Phase 2 – tests on several hundred participants with the disease/condition for up to two years to monitor effectiveness and side effects

Phase 3 – tests on 300 to 3,000 participants with the disease/condition for one to four years to monitor effectiveness and any negative reactions

Phase 4 – tests on several thousand participants with the disease/condition to monitor safety and effectiveness

Q: How can I participate in a clinical trial?

A: Who can participate varies with each study. Some clinical trials want healthy participants, others want people with a specific disease or condition, and some want a predetermined group of people. The eligibility criteria are outlined in the plan, or protocol, of each clinical study. For more information on participating in a clinical trial, visit To find a trial near you, visit or ask your doctor.

Q: What are the risks of participating in a clinical trial?

A: Depending on the trial, there may be serious or life-threatening side effects. These risks will be outlined in a consent document to participants prior to joining. Clinical studies can also take a significant amount of time, effort, and travel. Not all insurance companies will cover the cost of participating in a clinical trial.

Q: Can I get paid to do a clinical trial?

A: Some clinical trials offer monetary compensation for participants’ time and effort. They may also cover any out-of-pocket costs. The trial will notify participants beforehand of any monetary compensation offered.

Related: Clinical Trials INFOGRAPHIC

Sources, FDA. gov,,