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Clinical trials

Clinical trials help identify potential new treatments to improve people’s health and save lives. Our progress is due in large part to the important and tough scientific questions we set out to answer with our trials and collaborations.

What are clinical trials?

Clinical trials are research studies with volunteers designed to learn more about how our bodies respond to potential new medicines or treatments. We’re grateful to the thousands of volunteers who participate in our clinical trials — making our research possible.

What clinical trials do and why they're needed

Clinical trials test medicines, vaccines or medical devices that are in development to see to see if they're safe and effective. It may take many clinical trials all around the world to understand which treatments work and how they work. New treatments are tested in clinical trials before government agencies can approve them for doctors to prescribe to people.

Clinical trials are a key part of the drug development process and our goal to:

Help save and improve lives

Learn more about how our bodies respond to investigational treatments

Find new and better ways of advancing science

Reasons to consider participating in a clinical trial

male patient being treated by female nurse and female patient being treated by a female doctor

Trial participants will:

  • Learn more about their health condition and take an active role in their own health care
  • Help future patients by advancing medical research

You're never required to join or complete a clinical trial. Trials are volunteer-only, and you may leave a trial at any time.

Risks include:

  • Unwanted side effects
  • The treatment may not work
  • You may not receive the new treatment being studied
  • Extra time and attention needed for trial-related tasks and visits

Learn more about how to join a clinical trial

Woman patient talking with health care provier

There are clinical trials in progress

Our medical advances can only happen through the efforts of many people, especially those who volunteer for clinical trials. They’re our partners in research.


Expanded Access Programs (EAP)

Participation in clinical trials is a primary route by which patients get access to investigational medicines and contribute to the collection of safety and efficacy data needed to support regulatory approval worldwide. For patients with a serious or life-threatening condition who are ineligible or unable to participate in a clinical trial, use of an expanded access program may be an option.

a patients medical team meeting

Policies and perspectives

We’re committed to disclosing balanced, complete and accurate information about our registered clinical trials of marketed products, regardless of outcome.


The four phases of clinical trials

Clinical trials require four phases, in addition to government review and approval, to ensure the treatment being studied is safe and effective. Each phase answers a different set of questions. See our infographic on how we take a research study from trial to treatment.

Clinical trials

Clinical trials take time and resources

  • A treatment may take several years to move from a phase 1 trial to government approval for doctors to prescribe it
  • Clinical trials require financial investment from sponsors. Merck is the sponsor of a variety of clinical trials for various diseases and conditions
  • Thousands of people in many countries contribute to clinical trials, including patients, researchers, health care professionals and support staff

Our work in clinical trials