Everything You Need To Know About Participating In Clinical Trials

Why participate in clinical trials? Learn everything you need to know before applying and participating in clinical trials in our comprehensive guide.

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Reviewed by Susan Egbert, PharmD

Published 20 December 2023

Clinical trials assess the outcomes of medical intervention, whether it be new drugs, surgical treatment, or changes to a person’s lifestyle. By participating in a clinical trial, an individual can be one of the first to try new treatments, usually at zero cost. However, it is important to have a full understanding of what a clinical trial entails before agreeing to participate in one.

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In this article, we will discuss everything you need to know about participating in clinical trials. We will look at the different types of clinical trials and clinical studies, who conducts them, where they are conducted, the duration of the trial, how to volunteer for a clinical trial and more. 

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What Is a Clinical Study?

Clinical trials and observational studies are research programs that assess medical conditions, illnesses, and the general health of participants. People taking part in a clinical trial receive medical intervention and are monitored over time to determine its outcome. The intervention could be a drug, surgery, therapy, or even a placebo. Over the course of the trial, information is gathered to assess any changes in the patient, positive or negative.

What is a clinical trial?

The medical intervention that is given to a participant is decided by the research plan (referred to as the protocol) that is created by the investigation/research team. The most common trial is a new medical procedure being tested against one that is regularly prescribed, and a placebo that does not contain any active ingredients or offer any medical benefits.

Any drug used in a clinical trial needs to be Food and Drug Administration (FDA) approved to be deemed safe. However, there are also studies outside of FDA-approved clinical trials for experimental drugs which are known as expanded access. This may be an option for anyone who was deemed ineligible for a normal clinical trial. There are also behavioral, surgical, and other medical clinical trials that do not involve taking any medication.

The goal of each trial is to determine the effectiveness and safety of new treatments, as well as:

  • Determining if a medical intervention has less severe side effects
  • If the intervention has a quicker recovery time
  • If diseases or conditions can be identified earlier
  • If there are new approaches that can prevent certain health issues
  • If a person’s quality of life can be improved
  • Assessing the need for caregivers or support groups.

Types of clinical trials

Prevention trials

A prevention trial examines the effectiveness of new drugs and treatments in terms of preventing a condition from developing, these can include for example, Alzheimer’s disease or dementia. These trials help to slow or stop the symptoms of the condition, or make it easier to identify people who may be at risk.

Treatment trials

Treatment trials can help to make life easier for people who suffer from a condition such as HIV or AIDS, for example. The trial can test new drugs to better treat such viruses and improve medical researchers’ overall understanding to develop new medication in the future.

Screening trials

Screening trials review a new medical treatment or procedure on a group of participants who do not have the disease or condition that is being studied. This allows researchers to determine if the treatment is safe and if it is worth any further study.

What is an observational study?

Observational studies on the other hand do not test a medical intervention but may help to identify new prevention strategies or treatment options.

An example of an observational study is monitoring the impact of regular physical exercise on cognitive memory. Participants may be asked to follow a regular exercise regime and given monthly memory tests to check for any improvement.

Types of observational studies

Healthy volunteer studies

This type of study can also assess the effectiveness of new treatment and therapy by testing how a healthy person reacts to it. A healthy volunteer study allows researchers to develop a better understanding of how a disease or condition may develop and spread.

Biospecimen studies

Biospecimen studies provide insights into a health condition or disease by evaluating cells, tissue or fluids from a person who has the medical issue being studied, compared to someone who doesn’t. This helps researchers learn much more about diseases and the genes and proteins that are affected.


Surveys are a frequent tool in observational studies because they make it easy to gather large amounts of valuable data. This data has added-value because it comes directly from participants who can provide personal insights into their experience. Information can also be provided regarding a person’s background for added context when conducting research on specific populations.

A survey can also be used to identify eligible participants, gauging their overall interest in the trial and their current health status. This makes the recruitment process much quicker, helping to find individuals who are perfectly matched for the study.

Reasons for Conducting Clinical Trials

There are five main reasons for conducting a clinical trial:

  1. To assess one or more medical interventions, such as a new drug, medical device, surgery, therapy, or clinical approach. This can include interventions for diseases, conditions, and syndromes.
  2. Evaluating medical interventions that identify or diagnose certain conditions or diseases.
  3. Preventing the development or recurrence of diseases and conditions. This may be achieved with a new or alternative medicine/ vaccine, or simply a potentially beneficial lifestyle change.
  4. Finding new ways of identifying conditions and their potential risk factors to implement prevention measures early.
  5. Improving the quality of life and level of comfort of people with chronic illnesses via supportive care.

Who conducts clinical trials?

Clinical trials are conducted by principal investigators who are usually medical doctors. The principal investigator will be supported by a team of researchers which may consist of doctors, nurses, other healthcare professionals, and support/care workers.

Where are clinical trials conducted?

Clinical trials can take place in a wide range of locations, including:

  • Hospitals (both community and private)
  • Doctor’s offices and clinics
  • Cancer centers
  • Medical centers
  • Veterans and military hospitals

A clinical trial may take place in one or two different locations, or at hundreds of different sites across the country.

How Long Do Clinical Trials Last?

The length of a clinical trial can vary, ranging from a number of months to several years. The duration can be dependent on the type of study, the individual phase of the trial, the desired outcome, and how many people are taking part in the trial. 

Who Can Participate in a Clinical Trial?

Every clinical study has a set of standards that outline who can participate, with the protocol (research plan) defining the eligibility criteria for each trial or study. Many clinical trials and observational studies only require healthy participants, while some select a group of people who meet certain criteria such as specific age, medical condition, or other habits such as smoking.

How Are Participants Protected in a Clinical Trial?

Before enrolling in a clinical trial, it is important to know how you are protected should anything go wrong. Therefore, it is important to find out as much about the trial as possible. Once you feel comfortable with the terms and conditions of the trial and understand the potential risks, you will then be in a position to sign the consent form.

Informed consent form

The consent form acts as confirmation that you understand the risks of a clinical trial, what you might gain from the trial, the schedule, location, and other details regarding the study. Unless the consent form has been signed, a person cannot take part in a clinical trial.

Monitoring clinical trials

Most clinical trials will be monitored by an institutional review board (IRB) and some may also be overseen by a data monitoring committee, usually referred to as a data safety and monitoring board. However, to ensure the safety and protection of participants, federal agencies may also observe how the trial is conducted.

For example, the Office of Human Subjects Research Protection and the FDA has the authority to decide whether a clinical trial sponsor is conducting the trial properly and that participants are sufficiently protected. If not, these agencies have the power to cancel the trial.

Questions to Ask Before Participating In A Clinical Trial

There are a number of important questions to ask before participating in a clinical trial to ensure you are well informed about what to expect. Some of the most important questions are:

  • What is the purpose of the study?
  • What medical intervention(s) will I receive?
  • How do you choose what intervention I will receive?
  • What are the chances of the intervention being ineffective?
  • Has the intervention been tested previously?
  • How do the side effects and risks compare to my current treatment?
  • What is expected of me during the trial?
  • What tests and procedures are involved?
  • How often will I need to visit the clinic/ hospital?
  • Will I need to be hospitalized?
  • Who will oversee my medical care during the trial?
  • What is the duration of the study?
  • Who will cover the costs of my participation?
  • Will I be reimbursed for expenses such as transport?
  • What long-term follow-up care will be needed after the trial?
  • Will the trial results be shared with me?
  • How am I protected if I am injured or suffer long-term damage as a result of the trial?

How Clinical Trials Vary

Clinical trials can vary because of a number of factors, ranging from the reason for conducting the study to the eligibility criteria. Other factors could include the number of people participating in the trial, the schedule of the trial (including the drugs, dosages, tests, and procedures), compensation for time spent participating in the clinical trial and the overall length of the study.

Do Participants in Clinical Trials Get Paid?

Participating in a clinical trial is a commitment that will require time and effort, for example, a person might need to travel to the study site a number of times. Occasionally, an overnight stay may also be required and a participant may also spend hours at a time undergoing tests or receiving treatment. This is why compensation for participating in a clinical trial is typically offered in some form. 

In most clinical trials, patients are not required to pay any out-of-pocket costs associated with the study. Although each trial is different, the trial sponsor would typically pay for any trial-related costs and additional testing.

Compensation may be provided in the form of:

  • Reimbursement for out-of-pocket costs such as travel, meals, and accommodation.
  • Compensation for the time spent participating in the trial, usually calculated on an hourly basis or flat rate per study visit. The compensation offered should always be of a reasonable amount so it is not deemed coercive.
  • Additional compensation may be offered if a treatment involves an invasive procedure and presents significant risk.
  • In some cases as a thank you, participants may also receive a gift or token in the form of a voucher, gift card, or branded merchandise.

Other Considerations for Clinical Trial Participation

Anyone thinking about participating needs to consider what the direct medical benefits of participating in a clinical trial will be and whether it is worth the time and effort. A clinical trial may have an impact on a person’s quality of life, including undesirable side effects, stress, and anxiety. A clinical trial is a commitment and to better track the side effects, researchers may need a long-term follow up period. 

There are also social and ethical factors to consider such as offering support to a clinical study and experimental drug that may or may not help future patients. During the trial, a considerable amount of personal health information will also be collected, therefore, it is important to know how this data will be used, who can access it, and how it will be protected.

Anyone eligible for a clinical trial should seek confirmation on what access to treatment they will have upon the conclusion of the trial, especially if it could provide long-term benefits. It is also important to establish their insurance coverage for clinical trials, including the cost of the trial and their healthcare requirements.

Frequently Asked Questions (FAQs)

Is It Safe to Participate in Clinical Research?

When considering the safety of a clinical trial you should check that the trial is regulated by the federal government and safeguards have been put in place by the institutional review board (IRB) and Human Subjects Research Protection Program.

What are the possible risks of participating in a clinical trial?

As with any medical treatment, a participant may encounter a number of side effects that can range in severity. This could result in a person feeling very ill and perhaps needing to take time off work. Before agreeing to participate in a clinical trial, participants also need to be aware that the chances of success are low. However, in some cases, trying an alternative treatment is worth the risk.

What percentage of clinical trials are successful?

Unfortunately, around 90% of new drugs that are studied in a clinical trial fail and it takes around $1bn and ten-to-fifteen years to develop a new drug. If the side effects of an experimental drug are too strong then it might never reach the approval stage.


Although the success rates of clinical trials are rather low, the potential benefits in terms of receiving more effective treatment and reduced side effects are sometimes worthwhile. Before giving consent, a participant should understand as much as possible about the study, including the potential benefits, possible expenses, and how individuals will be protected.

As each trial is different, it is recommended to talk with the trial sponsor and ask them as many questions as possible to determine what will be expected from you, as well as the potential level of risk involved.

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