Clinical Trial FAQs

What is clinical research and why is it done?

Clinical research is medical research that studies people to understand health and disease. Clinical research helps improve the way doctors treat and prevent illness. Through clinical research, researchers learn:

• How the body works
• How illness develops in people, such as how diseases get better or worse over time
• How the body handles a possible treatment
• Which behaviors help people stay healthy and prevent illness, and which behaviors raise the chance of illness

The goal is to use science to improve people’s health care and health over time. The participants who join and take part in clinical research studies may or may not get any benefit for themselves.

Clinical trials are research studies in which researchers assign participants to get one or more interventions to test what happens in people. Because of this, clinical trials are also called interventional studies. Often, the intervention is investigational, which means it is not approved for doctors to prescribe to people.

In some clinical trials, researchers assign participants to interventions randomly. This means that researchers assign the participants by chance. Usually, participants (or their doctors) don't choose what intervention they will get when they join a clinical trial.

Should I participate in a clinical trial? 

Choosing to participate in a study is an important personal decision. If you are considering joining a study, get answers to your questions and know your options before you decide. The NIH Clinical Research Trials and You website is a resource for people who want to learn more about clinical trials. It includes a list of what questions to ask if offered a clinical trial and can help you get information from the research staff to decide if you will join a study. You may also want to talk with your doctor and family or friends about deciding to join a study.

Who can join clinical research?

Researchers look for people who fit a certain description, called eligibility criteria. These criteria give details on who can and cannot join a study and could include:

• People of a certain age or sex
• People who do or do not have a certain illness, disease, or health condition
• People with or without a certain health history, such as a prior treatment
• People who are exposed to or are in contact with something that affects their health

Researchers use eligibility criteria to keep participants safe and enroll the right participants to collect the data they need to answer the research question. There are many kinds of research studies, all with different types of eligibility criteria.