Clinical Trials and How They Work

Clinical Trials and How They Work

One of the biggest barriers to progress when it comes to finding and developing new treatments for both acute and chronic illnesses is a lack of participant enrollment in clinical trials. If there aren’t enough participants to start the study, or to provide enough significant data, the study doesn’t happen, and the time and money that went into setting it up is wasted. 

Participating in a clinical trial does require commitment, and not everyone can commit, but for those who can, joining a clinical trial is the single most effective way to move research forward and expedite solutions. Here is some basic information about what clinical trials are, how they work, and what it means to participate in one.*

What are clinical trials?

Clinical trials help doctors and scientists learn about experimental drugs and other therapeutic devices, including how well they work and how safe they are for human use. Clinical trials may study the study drug by itself, or compare it to either an approved medication or a placebo. 

Clinical trials play a vital role in discovering new, viable treatment options for both acute and chronic diseases. In the United States, all new medications must undergo multiple phases of research before they can be evaluated by the Food and Drug Administration.

Before enrolling in a clinical trial

Before enrolling you in a clinical trial, the trial doctor will provide you with a packet of information about that trial, as well as an ‘informed consent’ form. Every clinical trial is different so it is important to always read all the information that is provided, and ask questions about anything you don’t understand, before signing the form.

Prospective participants will always be informed of the procedures that they can expect to undergo before they decide to join the clinical trial.  Participation in a clinical trial is usually broken down in three separate stages: Screening, Treatment, and Follow-up.


The purpose of the screening period is to make sure participants are a good match for the trial. During the screening stage of most clinical trials you can expect to:

  • Read and sign the informed consent form prior to any trial-related tests or procedures 
  • Provide personal information, such as date of birth, sex, ethnicity, and race
  • Answer questions about current medical conditions and medications
  • Allow the trial doctor to take your vital signs such as blood pressure and heart rate 
  • Undergo a comprehensive physical exam and perform a lung function test 
  • Get blood drawn for routine laboratory testing 
  • Get an electrocardiogram to record the electrical activity of your heart

Some trials have lengthy screening periods involving multiple medical tests before you’re even deemed eligible to join the study, so be prepared for varying time commitments.


If you are deemed eligible to participate in the trial, the trial doctor will officially enroll you and give you the study drug, along with instructions on how to take it once you’re at home. During the treatment phase of the clinical trial, you will be expected to:

  • Use the study drug or other therapy as instructed
  • Avoid all medications, foods, and activities that are forbidden while taking the study drug
  • Attend all clinic or office visits as agreed
  • Complete health-related questionnaires that assess changes in symptoms

Participants are also expected to inform the trial doctor of any changes in health, including new or worsening medical conditions, and any changes in medications while taking the study drug.


Participants will usually complete one last visit after they are done with the study drug, though some studies require months or years of follow-up with participants, whether through physical exams, phone calls, questionnaires, or a combination of the three.

Does it cost money to participate in a clinical trial?

You do not have to pay or have health insurance to sign up for a clinical trial. The trial drug and trial-related procedures are provided to participants at no charge to them or their health insurance companies. Clinical trials often compensate participants for their time and effort.

Participating in a clinical trial is always voluntary. Even after signing on, you can leave at any point during the screening or trial process.

*Learn About Clinical Studies. National Institutes of Health, U.S. National Library of Medicine. Retrieved from