People with the condition being studied as well as healthy people can volunteer to participate in a study.  The FDA has very strict requirements that specify which studies involve healthy volunteers and which studies involve patients with the condition being studied.

Each study has specific requirements such as age, sex, and medical condition for participants.  The physician conducting the study will review each volunteer’s medical history and the study requirements to determine who can participate.  Known risks and discomforts will be explained by the study physician prior to participating in the study.  In addition to the known risks, there may be unknown risks such as medication side effects involved in participating in a clinical study.  Study procedures, risks, and benefits are explained to volunteers during the informed consent.  (See GLOSSARY OF CLINICAL STUDY TERMS)