n Introduction to Clinical Trials for Participants
Frequently Asked Questions

Choosing to participate in a clinical trial is an important personal decision. The following frequently asked questions provide detailed information about clinical trials. In addition, it is often helpful to talk to a physician, family members, or friends about deciding to join a trial. After identifying some trial options, the next step is to contact the study research staff and ask questions about specific trials.

What is a clinical trial?

A clinical trial (also clinical research) is a research study in human volunteers to answer specific health questions. Carefully conducted clinical trials are the fastest and safest way to find treatments that work in people and ways to improve health. Interventional trials determine whether experimental treatments or new ways of using known therapies are safe and effective under controlled environments. Observational trials address health issues in large groups of people or populations in natural settings.

Why participate in a clinical trial?

Participants in clinical trials can learn more about a disease or health care condition and help others by contributing to medical research

Who can participate in a clinical trial?

Before joining a clinical trial, a participant must qualify for the study. All clinical trials have guidelines about who can or cannot take part. Guidelines on who can be included in the study are called inclusion criteria. Guidelines on who must be excluded from the study are called exclusion criteria. Using these criteria is very important to help make sure that the research helps to produce reliable results. Some of these criteria are factors like age, gender, the type and stage of a disease, previous treatments, and other health conditions. Some research studies need people with illnesses or conditions to be studied in the clinical trial, while others need healthy participants. It is important to note that inclusion and exclusion criteria are not personal. Instead, they are an unbiased way to identify appropriate participants for the study. The criteria help ensure that the study is ethical and that researchers will be able to answer the questions they plan to study.

What is informed consent?

Informed consent is the process of learning the key facts about a clinical trial before deciding whether or not to participate. It is also a continuing process throughout the study to provide information for participants.

To help someone decide whether or not to participate, the doctors and nurses involved in the trial explain the details of the study. If the participant’s native language is not English, translation assistance can be provided. Then the research team provides an informed consent document that includes details about the study, such as its purpose, duration, required procedures, and key contacts. Risks and potential benefits are explained in the informed consent document. The participant then decides whether or not to sign the document. The informed consent document is not a contract, and the participant may withdraw from the trial at any time.

What are the benefits and risks of participating in a clinical trial?


Clinical trials that are well-designed and well-executed are the best approach for eligible participants to:

  • Help others by contributing to medical research.
  • Learn more about a disease or health care condition.
  • Obtain study related medical care at leading health care facilities during the trial.


There are risks to clinical trials.

  • There may be unpleasant, serious or even life-threatening side effects to the investigational drug or device.
  • The investigational drug or device may not be effective for the participant.
  • The protocol (study plan) may require significant time and attention, including trips to the study site, tests, hospital stays or complex dosage requirements.

What are side effects and adverse reactions?

Side effects are any undesired actions or effects of a drug, device or medical procedure. Negative or adverse effects may include headache, nausea, hair loss, skin irritation, or other physical problems. Experimental drugs and devices must be evaluated for both immediate and long-term side effects.

What should people consider before participating in a trial?

People should know as much as possible about the clinical trial and feel comfortable asking the members of the study team questions about it, the care expected while in a trial, and the cost of the trial.

The following questions might be helpful for the participant to discuss with the study team. Some of the answers to these questions are found in the informed consent document.

  • What is the purpose of the study?
  • Who is going to be in the study?
  • Why do researchers believe the drug or device being tested may be effective? Has it been tested before?
  • What kinds of tests and procedures are involved?
  • How do the possible risks, side effects, and benefits in the study compare with my current treatment?
  • How might this trial affect my daily life?
  • How long will the trial last?
  • Will hospitalization be required?
  • Who will pay for the study procedures?
  • Will I be reimbursed for other expenses?
  • What type of long-term follow up care is part of this study?
  • How will I know that the study drug or device is working? Will results of the trials be provided to me?
  • Who will be in charge of my care?

What kind of preparation should a potential participant make for the meeting with the research coordinator or doctor?

  • Plan ahead and write down possible questions to ask.
  • Ask a friend or relative to come along for support and to hear the responses to the questions.

Does a participant continue to work with his or her primary health care provider while in a trial?

Yes. Even though some clinical trials provide short-term procedures related to a designated illness or condition, in general, clinical trials do not provide extended or complete primary health care. In addition, by having his or her regular health care provider get in touch with the research team, the participant can ensure that other medications or treatments will not conflict with the protocol.

Can a participant leave a clinical trial after it has begun?

Yes. A participant can leave a clinical trial, at any time, with no penalty or loss of benefits. When withdrawing from the trial, the participant should let the research team know about it, and the reasons for leaving the study.

Who sponsors clinical trials?

Clinical trials are sponsored or funded by a variety of organizations or individuals such as physicians, medical institutions, foundations, voluntary groups, pharmaceutical companies and device manufacturers. In addition, federal agencies such as the National Institutes of Health (NIH), the Department of Defense (DOD), and the Department of Veteran’s Affairs (VA) sponsor clinical trials. Trials can take place in a variety of locations, such as hospitals, universities, doctors’ offices, or community clinics.

What is a protocol?

A protocol is a study plan on which all clinical trials are based. The plan is carefully designed to minimize the impact on the health of participants as well as answer specific research questions. A protocol describes what types of people may participate in the trial; the schedule of tests, procedures, medications, and dosages; and the length of the study. While in a clinical trial, participants are seen regularly by the research staff to monitor their health and to determine the safety and effectiveness of the study drug or device.

What is a placebo?

A placebo is an inactive pill, liquid, or powder that has no treatment value. In clinical trials, experimental treatments are often compared with placebos to assess the treatment’s effectiveness. In some studies, the participants in the control group will receive a placebo instead of an active drug.

What are the phases of clinical trials?

Clinical trials are conducted in phases. The trials at each phase have a different purpose and help scientists answer different questions:

In Phase I trials, researchers test a new drug or treatment in a small group of people (20-80) for the first time to evaluate its safety, determine a safe dosage range, and identify side effects.

In Phase II trials, the study drug or treatment is given to a larger group of people (100-300) to see if it is effective and to further evaluate its safety.

In Phase III trials, the study drug or treatment is given to large groups of people (1,000-3,000) to confirm its effectiveness, monitor side effects, compare it to commonly used treatments, and collect information that will allow the drug or treatment to be used safely.

In Phase IV trials, post marketing studies delineate additional information including the drug’s risks, benefits, and optimal use.

What is an “accredited” IRB?

Certain IRBs have been “accredited” by private accreditation agencies. In an accreditation process, experts in a particular field define standards of acceptable performance for organizations in that field. Then the experts measure how well organizations meet the expectations. Accreditation is used often in education and medicine, but has also expanded into other areas. The accreditation of IRBs began several years ago.

One of the goals of accreditation is the improvement and continuing education of the organizations that seek it. Accreditation is usually voluntary and is granted for a specific period of time, generally three or more years, following which the organization must repeat the process. Accreditation is a long-term, continuous activity, both for the accrediting body and for organizations under review. Protecting the public is the goal of accrediting organizations.

Additional information can be found at the following websites:…RunningClinicalTrials/GuidancesInformationSheetsandNotices