What is Clinical Research?

Clinical research is carefully supervised human research designed to answer scientific questions about health, illness, and possible medical approaches.

A smiling caregiver hugs a patient who has learned about a research study he may qualify for.

What is a Clinical Study?

One of the most important steps in the development process is the clinical study, a research study that collects information from people to answer a specific medical or scientific question. You may hear people call these things clinical research, clinical trials, or clinical studies. They all mean the same thing. Through clinical studies, investigational drugs are tested to answer whether they can safely and effectively benefit human beings. But before this can happen, people must volunteer and participate.

The process that brings a potential new drug from the research laboratory to the marketplace is a long and careful one. Long, because it takes years to complete all the laboratory, animal and human tests; careful, because all those involved in bringing it to market must ensure patient safety and follow strict government regulations in evaluating the drug's safety and efficacy.

Types of Clinical Studies

There are two broad categories of clinical studies.

Interventional
Observational

Interventional

The research team assigns participants to a study intervention, such as an investigational medicine, device, procedure, test, or other study activity. Researchers collect information during the study.

Observational

The research team collects information about people’s health over time. The research team does not assign a study intervention.

Phases of a Clinical Study 

Typically, potential new medicines and treatments are tested in four phases. Each phase is designed to answer specific questions and builds on what was learned in the phase before it.

Not every study follows this exact path. Some studies, particularly observational studies, do not use a phased approach at all. The study team will always be available to explain which type of study you are being invited to join and what that means for your participation.

A doctor and a patient discuss how to sign up for clinical studies and the potential benefits of a study.
Step 1
Phase 1

The first time an investigational medicine is tested in people, usually in a small group of healthy volunteers. Learn more here.

Step 2
Phase 1/2

A combined study that starts small to check that the investigational medicine is safe, then opens up to more people who have the condition being studied. Learn more here.

Step 3
Phase 2

The investigational medicine is given to a larger group of people who have the condition it's meant to treat, to see if it's working and to figure out the right dose. Learn more here.

Step 4
Phase 2/3

A combined study that first determines the dose and methods to receive the investigational medicine, then expands to confirm if the investigational medicine or study drug is both safe and effective for patients. Learn more here.

Step 5
Phase 3

The biggest studies, involving the largest number of patients, designed to confirm that the investigational medicine works and is safe. Results from this phase are typically reviewed when deciding whether to approve an investigational medicine or study drug. Learn more here.

Step 6
Phase 4

After an investigational medicine has been approved, these studies continue to monitor how it performs in the real world. Learn more here.

Safety and Oversight

Research done through clinical studies is carefully supervised, monitored, and documented. Before a study can begin, it must be reviewed and approved by an Institutional Review Board (IRB) or ethics committee. These are independent committees made up of medical professionals, ethicists, and community members whose job it is to protect the rights and welfare of study participants.

Investigational drugs must also demonstrate their safety and efficacy to government regulators (such as the Food and Drug Administration in the United States) before they are approved.

People who choose to take part in a study play an important role in this process.

Learn more about our Commitment to Patients and your rights as a study volunteer.

Questions to Consider

What is the purpose of clinical studies?
1

Clinical studies help to advance medical knowledge and develop potential new treatments or interventions, including:

  • Potential new medicines or new ways of using existing medicines
  • Investigational medical devices
  • Investigational surgical methods
  • Effects of behavioral changes (e.g., changes in habits, diet, or exercise)

The purpose of clinical studies is to test the safety and efficacy of these potential new treatments. Clinical research involves voluntary human participants, who may have specific health conditions or may be “healthy volunteers.” There are many regulations in place to protect the safety, privacy, and wellbeing of clinical study volunteers.

What are the risks when joining a clinical study?
2

Remember that there are risks associated with clinical studies. Investigational drugs are tested in clinical studies because not everything is yet known about them. There may be risks to receiving the drug that will not be uncovered until after a clinical study begins. You can discuss these considerations with your doctor.

Where do clinical studies take place?
3

Clinical studies can occur in a variety of places. Some are performed in a hospital and others right in the doctor's office or special research centers. Additionally, some or all parts of a study may be conducted remotely at home or through a local healthcare provider.

Who pays for a clinical study?
4

In most cases, the clinical study sponsor pays for everything, with the exception of any standard-of-care treatment (medications a patient would have received even if they were not in a study) for the patient. The informed consent document and study team should explain which study-required procedures or investigational medicine, if any, are provided at no cost to qualified participants.

How do I decide to participate in a clinical study?
5

Only you can decide whether or not to participate in a clinical study. Participation in a clinical study can be a great undertaking, and there are no guarantees that the investigational drug will work. Understanding what participation involves can help you make choices about your health and care that are right for you. If you do choose to participate in a study, that participation is always voluntary. You can choose to leave a study at any time, for any reason.

How do I join a clinical study?
6

Not every disease will have a clinical study currently underway. But this situation is constantly changing. Talk with your doctor, healthcare provider, or patient support group to learn if research is being planned that may be appropriate for you.

Learn more about participation in clinical research studies.

What is the purpose of clinical studies?

Clinical studies help to advance medical knowledge and develop potential new treatments or interventions, including:

  • Potential new medicines or new ways of using existing medicines
  • Investigational medical devices
  • Investigational surgical methods
  • Effects of behavioral changes (e.g., changes in habits, diet, or exercise)

The purpose of clinical studies is to test the safety and efficacy of these potential new treatments. Clinical research involves voluntary human participants, who may have specific health conditions or may be “healthy volunteers.” There are many regulations in place to protect the safety, privacy, and wellbeing of clinical study volunteers.

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Last updated August 3, 2026.