Common questions about clinical trials

You should be sure to ask questions about any clinical trial in which you consider participating. These are some of the most common questions people ask before becoming involved in a clinical trial:

Are clinical trials safe?

Clinical trials follow standards and are highly regulated to protect participants. Every trial is closely monitored by an independent ethics committee or Institutional Review Board to safeguard the rights and welfare of participants. Nevertheless, clinical trials cannot be risk-free. Although safety precautions are in place to protect people who participate in clinical trials, your condition or health could remain the same, improve or get worse.

What are the phases of clinical trials?

Clinical research is done in phases. A drug or treatment being studied in a clinical trial is considered investigational or experimental because it has not been approved for use.

  • Phase I trials evaluate safety and collect information about side effects. Some phase I clinical trials only look for healthy volunteers who may be compensated for participating.
  • Phase II trials evaluate the effectiveness of the investigational drug, procedure or device and collect additional information about safety and side effects. Often this is the first time a drug is tested in people living with the disease.
  • Phase III trials evaluate a drug or treatment in large groups of people worldwide to confirm effectiveness, monitor side effects, compare it to commonly used treatments and collect additional information that will allow it to be used safely.
  • Phase IV trials take place after a drug or treatment is approved for use. These trials provide additional information about risks, benefits and the best use of the drug, treatment or device.

What are the potential benefits & risks of participating in a trial?

Although there are no promises of direct benefits, people choose to take part in clinical trials for a variety of reasons, such as:

  • Close monitoring of health conditions
  • Prior treatments have been unsuccessful
  • The chance to receive an investigational drug or treatment not available outside the trial
  • Support for medical and scientific progress
  • Better understanding of health conditions
  • Help and hope for future patients
  • Information about support groups and other resources
  • Reimbursement for time and travel expenses


Potential risks or drawbacks from being in a clinical trial may include, but are not limited to:

  • Side effects from investigational drugs, treatments or medical procedures
  • Health conditions getting worse or staying the same
  • Expenses for things like travel, childcare or medical procedures not covered by insurance
  • Frequent or long medical appointments

How can I be sure that I understand what will happen in a trial?

The research team will explain the trial to you and review an informed consent document (ICD) with you. This document describes what will happen during the trial. Participating in a clinical trial is completely voluntary. As such, you can take as much time as you need to ask questions and review the ICD before deciding if you want to be in the trial. If you decide to join the trial, you will be asked to sign the ICD. The informed consent document is not a contract. By signing the document, you show that you have been told all the details and want to be part of the study. You will receive a copy of the ICD to keep for your reference. You can also ask questions throughout the trial so that you continue to understand what will happen at each visit and along the way to completion. It is also important to know that even after signing the ICD, you may withdraw your consent to participate at any point in a clinical trial.

How is it determined who can participate in a clinical trial?

If you want to be in a clinical trial, you will undergo a screening process to see if you meet all the requirements for participating in the trial. As part of the screening process, you will need to answer questions about your medical history, prior and current treatments and medications, and other issues that may affect your ability to participate in the trial. You may also need to have some medical tests and procedures done as part of the screening process. The research staff and physician(s) from the trial site will go over this information with you, and it will also be outlined in the informed consent document.

Can I leave a clinical trial once it has started?

Taking part in a clinical trial is voluntary. If the research team determines that you can be in the trial, you may choose to participate or not participate. If you choose to participate, you may change your mind at any time and leave the trial for any reason. This will not affect your regular medical care or any medical benefits you had before joining the trial.

What are my responsibilities in a clinical trial?

While taking part in a clinical trial, you will need to:

  • Follow instructions from the research team
  • Attend trial-related appointments
  • Complete scheduled activities, such as recording when you take your medication
  • Inform the research team about any changes to your health or study medication side effects
  • Comply with trial-specific requirements, as described in the informed consent document


Some people need help from loved ones or care partners to participate in a clinical trial. A child, an elderly person, or someone whose health condition makes certain activities more difficult all deserve the same clinical trial opportunities that others have. Your loved one or care partner may be asked to:

  • Help you follow trial requirements
  • Assist you with administering an investigational drug or treatment
  • Assist you with completing trial-related activities
  • Keep track of changes in your health
  • Bring you to trial appointments
  • Communicate with the research team on your behalf

What is an investigational drug or treatment?

An investigational drug or treatment is not yet approved for the use being studied, and can only be given as part of a clinical trial.

What is a placebo?

A placebo looks like an investigational drug but contains no active medicine. A placebo is often used in a clinical trial to help evaluate an investigational drug by comparing the effects seen in participants who take the investigational drug versus those who take the placebo.

What if I have questions during a clinical trial?

If you have questions or concerns about any aspect of the trial, you should feel comfortable discussing them with the research team at any time. You can also talk with your regular doctor about the clinical trial.

Can I see other doctors while I am in a clinical trial?

You can visit any doctor to meet your health needs during a clinical trial. You should tell other medical professionals you see that you are participating in a clinical trial and communicate openly with the research team about other care you receive.


Finding a clinical trial.
Trials for healthy volunteers
Trials with healthy volunteers are designed to develop new knowledge rather than to provide direct benefit. If you are a healthy adult, aged 18 or above, you can apply to be considered for paid participation in phase 1 interventional clinical trial studies. To register as a healthy volunteer, contact Fortrea / register with Fortrea here:
Trials for patients
Interventional clinical studies — studies that evaluate direct impacts of investigational treatments or preventive measures on diseases — are being run at research centers all over the world. As with any decision you make that may impact your health, speak with your doctor about finding and participating in a clinical trial. For more information about specific clinical trials, visit which provides a catalog of all registered clinical studies.