Answers to the most common clinical trial questions

A clinical trial is a type of research study designed to evaluate whether an investigational drug is safe and effective for use in humans. Participants are given specific medical treatments (or placebos) and researchers closely monitor the results to help determine if the drug should be approved for use. The U.S. Food and Drug Administration (FDA) has strict rules that govern how clinical trials are conducted, and requires that an investigational drug be proven safe and effective before it can be approved and widely used in the United States.
All clinical trials follow a plan called a protocol. A protocol is a written document that describes the rationale, objectives, design and organization of a clinical research trial. For example, a protocol describes the type of people who are eligible to participate, the length of the study, the required procedures and drug doses.
Every clinical trial has strict eligibility criteria listed in the protocol to help determine who can take part. This criteria is based on factors such as age, gender, type or stage of disease, medical history, use of other medications and the ability to perform certain activities. Whether an individual meets this criteria is assessed during the ‘screening’ period at the very start of a clinical trial. This may involve certain assessments and questionnaires. Importantly, a trial doctor is the person who determines whether someone is eligible to participate, not the study sponsor.
Yes. Participation in clinical trials is voluntary, and research participants can choose to discontinue their participation in a trial at any time.
Eligibility criteria help trial doctors to determine if an individual is right for a trial, but it’s just as important that the individual determines if the trial is right for them. That’s why every clinical trial has an informed consent process that potential participants must go through before they take part. This process involves providing individuals with enough information about the trial and enough time to allow for an informed decision about participation. This information is outlined in an informed consent form (ICF) that potential participants must read and sign before they can take part in the trial. This form includes key facts about the trial, like why it is being conducted and what the risks and benefits are of taking part. By signing this form, participants are showing that they understand what taking part involves. This form is not a contract – participants may leave the trial at any time.
Every trial is different, but usually participation is free. The trial sponsor often covers the cost of the trial drug and the necessary physician visits and tests performed for the study. Sometimes, participants’ insurance will be billed for care not related to the trial. Support for travel to clinic visits may also be provided.
People take part in clinical trials for a number of reasons. For example, they may benefit from the frequent health checks. They may also benefit from taking the investigational drug, although this cannot be guaranteed – the investigational drug may be better than, the same as, or worse than existing treatments. Many people also take part in clinical trials to contribute to medical research and our understanding of the disease.
Once a trial has been completed and researchers have appropriately analyzed the results, data from the trial are typically announced by the trial sponsor. Research participants can learn more about trial results from their physician. is a database that is independently operated by the U.S. National Institutes of Health to help patients and researchers locate and learn more about clinical trials. It lists privately and publicly supported clinical trials of human participants conducted around the world.