Clinical trials: What you need to know

A clinical trial is a research study that is designed to answer health questions. The research study is performed on human volunteers. This article explains some basics of clinical trials and gives you the pros and cons of participating.

There are several types of clinical trials

  • Treatment trials, test possible new treatments, including medications
  • Prevention trials, test approaches that will prevent a disease from happening or returning
  • Diagnostic trials, test possible new ways to diagnose a disease or medical condition
  • Screening trials, test new methods of learning whether you have a medical condition
  • “Quality of Life” or supportive trials, test how life can be improved for people with an illnesses

There are several phases of clinical trials

  • Phase 1 is early in the development of a new treatment or drug. A small number of people are in the trial to learn if dosages are safe and to examine side effects.

  • Phase II is when the treatment or drug is given to 100-300 people to see if it is both safe and effective.

  • Phase III is when more people, often thousands, are given the treatment or drug to learn if it is effective, see how it compares to other treatments, and learn what side effects occur.

  • Phase IV studies occur after the drug or treatment is marketed. These studies focus on the best use for the drug or treatment, the side effects, and the benefits.

What is it like to be in a clinical trial?

Because clinical trials test new treatments or procedures, there are strict rules, and all participants are volunteers. Only certain people will be eligible. Some studies require healthy volunteers, and others need volunteers with specific medical conditions. Your medical history and current treatments may allow you to participate, or exclude your participation in the trial.

Before you can begin, you must sign an “informed consent” form. This form tells you everything you need to know about the trial so you can decide if you want to participate, including:

  • What the research question is that the trial hopes to answer
  • Who is eligible for the trial
  • The names of the people responsible for the trial
  • What you will do if you participate
  • How long the trial will last
  • What the risks of the new treatment or procedure might be
  • What the benefits of the new treatment might be
  • What costs you might face
  • Who is paying for the trial
  • What circumstances might end your participation in the trial
  • Your right to stop participation at any time

What Is a clinical trial protocol?

Researchers follow strict study procedures during the trial, written in a document called the “study protocol”. The study may divide participants into two or more groups, and each group receives a different treatment. Assignment to a group is usually a random process (like tossing a coin) and participants may not know to which group they are assigned. The control group does not receive the drug or procedure being tested, but receives another drug or procedure, or a placebo. A placebo is a treatment that is not expected to have an effect. For example, in an experiment testing a new drug taken by mouth, you may not know if you are getting the new drug, a drug that is already being used for treatment, or a placebo, a pill with a harmless substance, like sugar.

Your doctor cannot change your group assignment. Your progress will be closely monitored in the study.

What are the pros of participating in a clinical trial?

You may want to participate in a clinical trial:

  • To gain access to a new drug or procedure
  • To have your health monitored closely
  • To potentially benefit others with your disease or condition
  • To be one of the first to experience a new procedure or treatment

What are the cons of participating in a clinical trial?

  • You may not be able to choose whether you receive the new treatment.
  • New drugs and procedures may cause side-effects that may worsen your present situation.
  • Not all side-effects or results are known and life-threatening conditions or side-effects can occur.
  • The trial may require an increase in the number of your medical visits.
  • The drug or procedure may not continue to be available to you after the trial.
  • Some health plans do not cover all of the costs of clinical trials.

Whether to participate in a clinical trial is a personal decision that you should discuss thoroughly with your doctor. Know as much as you can about your specific condition and the details of the trial, before you decide to join the trial. Your doctor can help you weigh the risks and benefits and assist you in deciding whether a clinical trial is right for you.


National Institutes of Health. (2007). Understanding clinical trials