How long do clinical trials take?

Clinical trials begin with an idea in a lab, with the goal of creating an FDA-approved treatment or device for the public. However, this process doesn’t happen overnight. While certain emergency situations require more swift action, here’s a closer look at how long the average clinical trial journey lasts.

Before the study begins

Basic research, drug discovery, and preclinical research for potential treatments typically start long before any clinical trial phase. Extensive research is conducted to decide whether the drug is a good candidate for clinical trials. Testing includes in vitro (in a test tube or cell culture) as well as in vivo (animal) experiments. For some drugs, researchers are able to perform drug profiling using computer models that show how the drug will interact with the human body.

Preclinical research may take anywhere from one to six years. Researchers only take the most promising potential treatments through the journey to market. New treatments then go through several clinical trial phases. These phases test the treatments for safety and effectiveness. 

How long do the phases of a clinical trial take?

Preclinical research investigates a drug’s safety and efficacy, but can’t always predict the ways the drug will interact with the human body. Let’s break down the phases of a clinical trial.

Phase 1: Phase 1 trials typically enroll 20 to 100 healthy volunteers or people with the condition being studied and last several months. This phase measures safety by testing for any adverse side effects of the treatment, but not necessarily how effective the drug or device is. 

Phase 2: Around 70% of potential new drugs pass Phase 1 and enter Phase 2, which continues to measure safety, while also looking at how effective the treatment is and carefully investigating side effects. Phase 2 trials recruit up to several hundred patients with the condition to take part. This phase typically lasts several months to two years.

Phase 3: Just 33% of drugs make it past Phase 2 and into Phase 3, which tests the potential treatment in the largest number of people. This phase measures both safety and effectiveness with many volunteers, sometimes thousands. Phase 3 trials last from one to four years.

FDA Approval: Approximately 25 to 30% of treatments move forward in the approvals process. After Phase 3, a pharmaceutical company may submit a New Drug Application (NDA) for the treatment to the Food and Drug Administration (FDA). The FDA then reviews results from all stages of the trial to determine whether it will approve the drug and allow the pharmaceutical company to begin marketing it to the public.

Phase 4: Phase 4 is often called “Post-Approval Research and Monitoring.” After a new treatment is approved by the FDA, the pharmaceutical or device company may want to continue monitoring patients to learn more about the treatment’s longer-term effects, while comparing it against other already-approved options. It may take time for long-term side effects to appear, making this an important phase.

Looking at the big picture, it takes approximately ten years for a new treatment to complete the journey from initial discovery to the marketplace. Clinical trials alone take six to seven years on average to complete.

A patient’s commitment to clinical trials

It’s important to have a clear understanding of what your role is when deciding whether to volunteer for research. Being seen as a partner in research is crucial at this time, with trust being a key component. 

When you're considering taking part in a clinical trial, ask the study team about the schedule of the trial. Some trials may last for several years, and require visits every few months. Other trials may be shorter but require more frequent visits, or for participants to make entries in an e-diary or paper diary in-between visits. You'll want to weigh the potential benefits of participation – access to a potential new treatment, contributing to science, and receiving compensation – against the time it may require of you and any potential side effects.

If at any point and for any reason you decide that the clinical trial is not for you, you're free to leave, even before the trial is completed. Some trials also end early if researchers aren't seeing the results they were hoping for.

The clinical trial process is long – and it's set up that way so that by the time drugs reach the public, they have been thoroughly evaluated. But the length of the process is one reason why it's so important for volunteers to take part. Without enough volunteers, up to 80% of clinical trials are delayed. Start looking for a clinical trial near you and help research move forward below.