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U.S. Department of Health and Human Services

For Consumers

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Clinical Trials and Investigational Drugs

If you’ve considered available FDA-approved treatment options and you still want to seek access to an investigational drug, there are two ways to do so:

  1. By participating in a clinical trial.
  2. By seeking access to investigational drugs outside of a clinical trial (expanded access).

Important Information about Clinical Trials

Clinical trials are studies of drugs that are still in development or have not yet been approved by the FDA for the use being studied. A drug being studied in a clinical trial is called an investigational drug.

What is a clinical trial?

In a clinical trial, a drug is evaluated to determine whether or not it is safe and effective. The drug may be compared with a placebo (a substance not expected to have any real medical effect) or a different treatment. Clinical trials are designed and intended to gather information about a drug that has not yet been proven to treat patients with a specific condition. 

Clinical trials of drugs provide information about:

  • Whether the drug has the effect it is supposed to have.
  • How much of the drug to give to a patient (also called the treatment dose) and how often (also called the treatment regimen).
  • What side effects are associated with the drug, and how they can best be managed.
  • How a drug is broken down in the body, and how long it stays in the body.
  • Which foods, drinks, or other drugs can be used at the same time, or should be avoided.

Clinical trial results allow the FDA to make decisions about whether or not a drug should be approved for marketing.  

Why do people participate in clinical trials? 

By participating in clinical trials, patients help advance what we know about new drugs. In doing so, clinical trial participants can play an important role in getting new drugs approved for use in treating other patients.

Many times, patients enroll in clinical trials so that they can gain access to new, experimental treatments – especially if all of their other treatment options have failed. Some patients may benefit from participating in a clinical trial if the investigational drug turns out to be effective.

It is important to remember that the main purpose of clinical trials is to study new drugs or new uses of approved drugs, not to treat patients. Often, drugs must be tested under very specific conditions, so not all patients with a given disease will be able to enroll in a clinical trial. In general, each clinical trial has inclusion and exclusion requirements that are intended to make the study more likely to demonstrate the effect of the treatment (such as excluding patients who are taking certain other drugs or who have other complicating disease conditions), or to protect patients by minimizing risks to certain populations (such as pregnant women). Additionally, a clinical trial for a specific drug is typically conducted at a limited number of institutions. Patients who live too far away from a research center may not be able to participate. If a patient is not eligible for a clinical trial or there are none near where they live, the patient may be able to obtain access to an investigational drug outside of a clinical trial.

Even among patients who do participate in a clinical trial, some may be treated with the investigational drug, and some may be treated with a placebo (a substance not expected to have any real medical effect), often along with existing standard of care, or a different therapy for comparison. Drugs that are being tested in clinical trials may not end up proving to be effective, or they may have unknown, sometimes severe, side effects.

If you are considering participating in a clinical trial, you should carefully read information about the drug trial you are considering and ask questions about exactly what will happen during the trial during a process known as "informed consent." You are entitled to receive detailed information regarding what is known about the drug before you decide to enter a clinical trial, and you must provide a signed informed consent document indicating that you understand what will happen during the clinical trial, before participating.

You should also get advice from your healthcare professional.

To learn more, see Basic Questions and Answers about Clinical Trials.

How can I learn more about clinical trials in my area?

The U.S. National Institutes of Health (NIH), through its National Library of Medicine (NLM), in collaboration with the U.S. Food and Drug Administration (FDA), maintains a public database of clinical trials at ClinicalTrials.gov. This easy-to-search web site lists thousands of clinical trials, and you can use it to find a study for a particular disease or condition. The site allows you to run searches to find clinical trials for specific illnesses, a specific investigational drug, or in specific areas of the country.


Contact FDA

Office of Health and Constituent Affairs

10903 New Hampshire Avenue

Bldg. 32, Room 5367

Silver Spring, MD 20993