All clinical trials have guidelines about who can participate. Before joining a clinical trial, a volunteer must qualify for the study. The factors that allow volunteers to participate in a clinical trial are called "inclusion criteria" and the factors that disallow volunteers from participating are called "exclusion criteria." These criteria can include age, gender, the type and stage of a disease, previous treatment history, and other medical conditions.

Some research studies seek participants with specific illnesses or conditions to be studied in a clinical trial, while others require healthy participants. It is important to note that inclusion and exclusion criteria are used to identify appropriate participants, promote participants' safety, and ensure that researchers learn the information they need.

When you join a clinical trial, you will receive research study visits, research-related tests and study medication at no cost, an opportunity to learn more about your medical condition and financial compensation for your time and travel.