A clinical trial is a research study that is done to whether a potential medical treatment is safe and effective. A potential medical treatment can be a drug, medical device, medical procedure, or a change in a person's behavior such as diet or exercise. People who take part in clinical trials are volunteers. They are also called "participants".

Clinical trials can help find new treatments that can improve people's health. When people participate in clinical trials, they help contribute to medical research that can find new or improved treatments for people with illnesses and diseases. The results of every clinical trial is important because it gives researchers more information about the risks and benefits of the treatments in the trial.

All clinical trials have rules about who can and cannot participate. These rules are called "eligibility criteria". The criteria are based on factors such as age, gender, the type and stage of a disease, previous treatment history, and other medical conditions. Eligibility criteria is not used to reject people personally. Instead, the eligibility criteria helps to make sure that the participants in the trial are safe and that the trial gets the most accurate information about the treatments being researched.

Some clinical trials seek participants with certain illnesses or conditions, while others need healthy participants.

Clinical trials are run and funded by sponsors. Sponsors can be organizations or individuals such as pharmaceutical companies, medical institutions, foundations, voluntary groups, and individual physicians. A clinical trial can have many sites that participate. The trial is led by a healthcare professional at each site, called the principal investigator. And there is usually a team of people, called the "research team" who work on each trial. Clinical trials can take place in a variety of locations, such as hospitals, universities, doctors' offices, or community clinics.

The costs for study treatments and study tests in the trial are usually covered by the research sponsor. This can include the treatment being studied, tests and physical exams, imaging scan or other assessments.
However, there can costs that are not covered by the sponsor. People who are considering participating in a trial can ask the research staff about any costs before agreeing to participate in a trial.

Potential benefits of participation may include:

• Receiving medical services such as physical exams, blood tests, or imaging scans
• Helping others by contributing to medical research

Examples of risks associated with participating in a clinical trial may include:

• The possibility of unpleasant, serious, or even life-threatening side effects
• The study treatment may not be effective
• The trial may require a great deal of time and effort, including trips to the study site, hospital stays, or complex dosage requirements

The benefits and risks of participating in a trial can be different for each study. People who are considering taking part in a trial can discuss the benefits and risks of the trial with the research team.

A protocol is the plan that the clinical trial must follow. The protocol is carefully designed to protect the health of the participants and answer specific research questions. A protocol describes:

• Protocols are reviewed by ethics committees and regulatory authorities such as the FDA.
• The length of the study
• The rules about who may or may not participate in the trial
• The schedule of tests, procedures, medications, and dosages
• The information the researchers want to collect about the study treatment

Informed consent is the process of learning about a clinical trial before deciding whether or not to participate. To help someone decide whether or not to participate, the doctors and nurses involved in the trial are required to explain the details of the study. They also provide a written document that includes details about the study including the purpose, risks and potential benefits, duration, required procedures, and important contact information. This document is called the "informed consent form".
People who are considering participating are allowed to take a reasonable amount of time to review the informed consent form. They can also ask the doctors and nurses any questions they have about the trial before deciding to participate. They can also talk with family, friends, or their personal doctor before they choose to participate.
Each person decides whether or not to sign the form and to participate in the trial, and no one should pressure or influence their decision in any way. If the participant is a child, then the parent(s) or guardian(s) will determine whether or not to sign the form and enroll the child in the trial. Depending on the age of the child, they may also have to sign what is called an assent form. Informed consent is not a contract and the participant may leave the trial at any time for any reason.

The conduct of clinical trials is governed by a system of laws, regulations and review processes which must be strictly followed. This is to ensure that all clinical trials are conducted in a safe and ethical manner, and that the rights of study participants are protected. All trials must follow a detailed study plan, or protocol, that tells the researchers what to do in the study.
The government has also established guidelines and regulations that require every clinical trial to be reviewed and approved by an independent committee to make sure that the trial follows the law and ethical standards. In addition to FDA review, clinical trial protocols are reviews by an independent institutional review board to ensure the safety of study participants.
Clinical trials must protect participants privacy and confidentiality. This means participants names and other identifying information about illnesses and behaviors are only known by a few people at the study site. The study sponsor is given coded information for their records, and the published results will not include information that identifies participants

Yes. A participant can leave a clinical trial at any time and for any reason. Although it is not required, the participant should let the research team know if they are leaving the trial and the reasons for leaving.

Yes. Most clinical trials provide study treatments related to a specific illness or disease for a short amount of time. But trials do not provide health care. When the primary health care provider works with the research team, together they can ensure that study participants continue to receive they care they need while participating in a clinical trial. Participants can talk to their research team about how their clinical trial data will be shared with their health care provider.

A placebo looks like a study treatment but does not have any medicine in it. Researchers use a placebo to help make sure any of the effects they see in the participants who take the real study treatments are actually caused by the study treatments. Not all trials use a placebo and the study plan and informed consent form must state if a placebo will be used in a trial.
Usually, researchers use a computer program to randomly choose the study treatment each participant received. This helps make sure the groups are chosen fairly. Researchers do this so that comparing the results of each study treatment is as accurate as possible.
Some clinical trials are "blinded". This can mean that neither the participant nor the study staff know what study treatment the participant is receiving- this is referred to as 'double-blinding'. Trials are done this way because knowing what study treatment the participants are getting can affect the accuracy of the results.

Clinical trials are conducted in steps that are called "phases". There are 4 phases of trials. Each phase has a different purpose and helps researchers answer different questions:

1. In Phase I trials, researchers test a new drug or treatment in a small group of people (20-80) for the first time to evaluate its safety, determine a safe dosage range, and identify side effects.
2. In Phase II trials, the study drug or treatment is given to a larger group of people (100-300) to see if it is effective and to further evaluate its safety.
3. In Phase III trials, the study drug or treatment is given to large groups of people (1,000-3,000) to confirm its effectiveness, monitor side effects, compare it to commonly used treatments, and collect information that will allow the drug or treatment to be used safely.
4. In Phase IV trials, post marketing studies delineate additional information including the drug's risks, benefits, and optimal use.