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How long do clinical trials take?

If you or someone you care for is considering participating in a clinical trial, typical questions you may have include:

  • How long do clinical trials take, in general?
  • How long does a phase 3 clinical trial take?
  • Do all trials take the same amount of time?

The length of a clinical trial varies, depending on what is being studied. Clinical trial length is described in the protocol. Read more about What is a clinical trial protocol?

As part of the process of informed consent, participants are told how long the study will last before they enroll.

How Fast Do Clinical Trials Work?

Clinical trials are not a guaranteed solution to disease. The length of a clinical trial generally increases with each clinical trial phase; phase 3 clinical trials are typically longer than phase 2 clinical trials.

How Long Does a Phase 1 Clinical Trial Take?

The length of a phase 1 study is typically several months.

How Long Does a Phase 2 Clinical Trial Take?

The length of a phase 2 study can span several months to 2 years. This phase involves up to several hundred people, with researchers looking for the effectiveness and safety of the drug over a relatively short period of time.

How Long Does a Phase 3 Clinical Trial Take?

The length of study for phase 3 clinical trials is usually 1 to 4 years. This phase involves 300 to 3,000 patients, with tests designed to determine the drug's longer-term effects.

How Long Does a Phase 4 Clinical Trial Take?

The length of study for phase 4 clinical trials can be the same as that for a phase 3 clinical trial or even longer.

Read more about the phases of clinical trials.

The Right to Withdraw at Any Time

Participation in a clinical trial is completely voluntary, so you have the right to withdraw from the clinical trial at any time, for any reason.

If you do stop your participation for any reason, you will continue to receive care and advice on your treatment options. You will be asked to return for a final evaluation by the trial doctor, which may include a physical examination and/or laboratory tests.

 

References:

  1. Step 3: Clinical Research. U.S. Food & Drug Administration website: https://www.fda.gov/ForPatients/Approvals/Drugs/ucm405622.htm#phases. Accessed April 3, 2018.