Clinical Trial FAQ — Common Questions Answered

A clinical trial is a carefully designed research study that tests a medical treatment, device, or approach in people. Trials follow strict rules reviewed by independent ethics boards to protect participants. Every approved medication you take today was once tested in a clinical trial.

Clinical trials can give you access to new treatments before they are widely available. You receive close monitoring from a research team, and you contribute to medical knowledge that helps future patients. Many participants report feeling empowered by taking an active role in their care.

You can search by condition here on TrialFinder, where eligibility criteria are translated into plain English. You can also search ClinicalTrials.gov, ask your doctor, or contact a patient advocacy group for your condition. Our guide on how to join a clinical trial walks through the full process.

Not always. Many trials allow you to contact the research team directly. However, discussing a trial with your doctor is a good idea because they can help you evaluate whether it is a good fit for your situation and coordinate your care if you decide to enroll.

There are four main phases. Phase 1 tests safety and dosing in a small group. Phase 2 evaluates effectiveness in a larger group. Phase 3 compares the treatment to existing options in hundreds or thousands of people. Phase 4 monitors the treatment after it has been approved. See our trial phases guide for details.

Eligibility varies by trial. Each study has specific criteria based on factors like age, gender, type and stage of disease, treatment history, and overall health. Some trials are broad, while others are highly specific. Being ineligible for one trial does not mean you are ineligible for others.

Inclusion criteria are the characteristics you must have to join a trial — for example, a specific diagnosis or age range. Exclusion criteria are factors that prevent you from participating, such as certain medications or coexisting conditions. These criteria exist to protect participants and ensure reliable results. Our eligibility guide explains how to read them.

It depends on the specific trial. Some studies exclude participants with certain conditions because those conditions could interfere with the results or increase risk. Others are designed specifically for people with multiple health issues. Check the eligibility criteria for each trial you are interested in.

No. Many trials specifically recruit children and adolescents. Pediatric trials have additional safety protections and require both parental consent and the child's assent when they are old enough to understand. Learn more in our guide to pediatric trials.

After enrollment, you will go through screening tests to confirm eligibility. Then you will be assigned to a treatment group, either randomly or by the research team. You will receive the study treatment and attend regular appointments for monitoring, tests, and check-ins with the research team.

Not necessarily. In randomized trials, you may be assigned to a control group that receives the current standard treatment or, in some cases, a placebo. The consent document will explain the odds of being in each group. In single-arm trials, everyone receives the new treatment.

A placebo is an inactive substance that looks like the real treatment. Placebos are only used when ethically appropriate — if an effective treatment already exists, the control group receives that treatment, not a placebo. You will always be told before enrolling whether a placebo is involved.

Visit frequency varies widely. Some trials require weekly visits, especially at the beginning. Others may only need monthly check-ins. Increasingly, some trials include remote monitoring and telemedicine visits. The schedule will be explained during informed consent before you commit.

This depends on the trial. Some studies require you to stop certain medications that could interfere with the treatment being tested. Others allow all current medications. Never change your medication regimen without discussing it with both the research team and your personal doctor.

Multiple layers of oversight protect you. An Institutional Review Board (IRB) approves the study before it begins. A Data Safety Monitoring Board reviews safety data throughout the trial. The FDA enforces strict regulations on trial conduct. You can leave at any time if you have concerns.

Yes, absolutely. You can withdraw from a trial at any time, for any reason, without penalty. This right is guaranteed by federal regulations and stated in every consent document. Leaving a trial will not affect your access to regular medical care.

Informed consent is an ongoing process where the research team explains the trial — its purpose, procedures, risks, benefits, and alternatives — and you voluntarily agree to participate. It is not just a form to sign; it is a conversation. You can ask questions at any point and take the document home to review. See our informed consent guide for details.

Report all side effects to the research team immediately, no matter how minor they seem. The team will assess the severity, adjust your treatment if needed, and provide appropriate medical care. Serious adverse events trigger additional safety reviews that may affect the entire trial.

Yes. Your medical information is protected by privacy regulations including HIPAA. Trial data is coded so that your identity is not linked to your results in publications or reports. Only authorized members of the research team and regulatory agencies can access your identifiable information.

The study treatment and trial-related tests are almost always provided free of charge by the trial sponsor. However, standard-of-care costs are typically billed to your insurance as they normally would be. Travel, lodging, and time off work may or may not be reimbursed depending on the study.

Most insurance plans, including Medicare, are required to cover routine care costs during a clinical trial. The experimental treatment itself is covered by the sponsor. Contact your insurance provider before enrolling to understand what will be covered and what your out-of-pocket costs might be.

No. While many trials are based at academic medical centers, research also happens at community hospitals, private clinics, and doctor's offices. Some trials now include remote participation with medications shipped to your home and virtual check-ins. Search by location to find trials near you.

Trial duration varies enormously. Some studies last a few weeks, while others continue for several years. Phase 1 trials tend to be shorter, while Phase 3 trials are often longer. The exact timeline will be outlined in the consent document before you decide to participate.

When a trial ends, the research team will discuss your next steps. You will transition back to standard care with your regular doctor. In some cases, if the treatment was effective, you may be offered continued access through an extension study or expanded access program.

You have a right to request a summary of the trial results once they are available. Many trials also publish their findings in medical journals and on ClinicalTrials.gov. Results can take months or years to analyze and publish after the trial concludes.

Sometimes. If the treatment is effective and the trial is complete, the sponsor may offer continued access through compassionate use or an open-label extension study while regulatory approval is pending. This is not guaranteed and depends on the sponsor and the regulatory situation.