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What are Clinical Trials?

Clinical trials (also known as clinical research) are research studies in human volunteers that investigate treatments and observe patient performance with new treatments. They play an important role in developing new treatment options for a variety of diseases. Before any new treatment can be tested in humans, it must have shown positive results in the laboratory and/or in animal studies. Interventional trials determine whether experimental treatments or new ways of using known therapies are safe and effective under controlled environments. Observational trials address health issues in large groups of people or populations in natural settings. The United States Food and Drug Administration (FDA) monitors most clinical trials to protect the participants and the general public. Ultimately, the FDA reviews and analyzes data from successful clinical trials to determine whether the experimental treatment should be approved for the treatment of a specific disease or disorder. Clinical trials may be carried out using completely new treatment options or using treatments that are already available. Clinical trials are the safest and quickest way to confirm whether new treatments are truly beneficial for patients.

Why are clinical trials important?

Clinical trials offer a look at future treatments. They determine whether a new and potentially better treatment is safe and effective in humans. Clinical trials may provide opportunities for you to receive a promising drug or treatment. Typically currently approved therapies are compared with new therapies and your doctor may feel this is an appropriate treatment for you.

Things you should know before participating in a clinical trial

Talk to your doctor

You should always discuss the benefits and risks of participating in clinical trials with your doctor.


Each clinical trial will have its own set of eligibility requirements. Your doctor will be able to help assess your eligibility for a specific trial.  

Informed Consent

The FDA requires that an individual read and sign an informed consent form before being enrolled in a clinical trial. Informed consent is a process that ensures patients are given complete information about a clinical trial prior to their participation. The key facts of the study are included in a written informed consent form for participants to read and discuss with their families and doctors. Be sure you understand all the facts before you sign the consent form. Don’t be afraid to ask questions!

Benefits and Risks of Clinical Trials

  • Potential Benefits:
    • There is the possibility that drugs or treatment program used in the trial will be better than currently approved treatment options
    • Patient care is provided by top doctors and researchers at leading health care facilities
    • You will have access to new treatment strategies that may not otherwise be available
    • Your progress will be closely monitored
    • Your participation may help to advance treatment of the disease
  • Potential Risks:
    • There is the possibility of unknown or unexpected side effects
    • There is always the chance that the new drug or treatment may be ineffective or less effective than current options
    • Participation in the clinical trial may require greater time commitment for treatment due to extra clinic visits for treatments or monitoring
    • You need to factor in the potential of additional costs that may be involved, such as housing and transportation, insurance payment for treatment outside covered network, etc.

Clinical Trial Phases

Phase I studies assess the safety of a drug or device. This initial phase of testing, which can take several months to complete, usually includes a small number of healthy volunteers (20 to 100), who are generally paid for participating in the study. The study is designed to determine the effects of the drug or device on humans including how it is absorbed, metabolized, and excreted. This phase also investigates the side effects that occur as dosage levels are increased. About 70% of experimental drugs pass this phase of testing. Phase II studies test the efficacy of a drug or device. This second phase of testing can last from several months to two years, and involves up to several hundred patients. Most phase II studies are randomized trials where one group of patients receives the experimental drug, while a second “control” group receives a standard treatment or placebo. Often these studies are “blinded” which means that neither the patients nor the researchers know who has received the experimental drug. This allows investigators to provide the pharmaceutical company and the FDA with comparative information about the relative safety and effectiveness of the new drug. About one-third of experimental drugs successfully complete both Phase I and Phase II studies. Phase III studies involve randomized and blind testing in several hundred to several thousand patients. This large-scale testing, which can last several years, provides the pharmaceutical company and the FDA with a more thorough understanding of the effectiveness of the drug or device, the benefits and the range of possible adverse reactions. 70% to 90% of drugs that enter Phase III studies successfully complete this phase of testing. Once Phase III is complete, a pharmaceutical company can request FDA approval for marketing the drug. Phase IV studies, often called Post Marketing Surveillance Trials, are conducted after a drug or device has been approved for consumer sale. Pharmaceutical companies have several objectives at this stage: (1) to compare a drug with other drugs already in the market; (2) to monitor a drug’s long-term effectiveness and impact on a patient’s quality of life; and (3) to determine the cost-effectiveness of a drug therapy relative to other traditional and new therapies. Phase IV studies can result in a drug or device being taken off the market or restrictions of use could be placed on the product depending on the findings in the study.

Where can you find information about current clinical trials?

In additional to our Clinical Trial Navigating Service, you can also go to . provides regularly updated information about federally and privately supported clinical research in human volunteers. gives you information about a trial’s purpose, who may participate, locations, and phone numbers for more details. You can use this site to find a wealth of information about clinical research, including listings of active industry and government-sponsored clinical trials, as well as new drug therapies in research and those recently approved by the FDA. Our site is designed to be an open resource for patients interested in participating in clinical trials and for research professionals.