Clinical Trials

How Long Do Clinical Trials Take

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Amie Sallah

Published 15 Dec 2022

How Long Do Clinical Trials Take - Infiuss Health


Clinical trials are a key part of drug development. During clinical trials, medications or procedures are tested in humans to ensure they work as intended and are safe for use. Clinical trial lengths vary greatly depending on the type of study and what stage it’s at in the drug development process.

Phase 1 trials: 2 to 3 years

Phase 1 trials are the first stage of testing a drug in humans. They test whether a drug is safe and how it's broken down by the body and what side effects it may cause. Between 20 and 80 healthy volunteers take part in these small, early-stage trials.

Phase 1 studies usually last around 2 years, but can be as short as 6 months or longer than 5 years for some drugs that need more time to develop.

During this phase:

  • The highest dose that's safe for humans is found; this helps decide how much of the medicine should be given to patients when they move on to phase 2 trials.

Phase 2 trials: 3 to 4 years

Phase 2 trials are the second phase of testing. This phase is used to test a drug on a larger group of people, which allows researchers to determine whether the results from Phase 1 trials were due to chance or not. If they find that the drug is effective and safe in Phase 2 trials, they will move on to Phase 3 trials. 

Phase 3 trials: 4 to 5 years

Phase 3 trials are the final step in testing a drug to determine whether it's safe and effective. Phase 3 trials usually involve large numbers of patients, and they take at least four years to complete. The drug companies are required to submit phase 3 results before they can apply for approval from the FDA.

Clinical trials can take a long time

The length of a clinical trial can vary a great deal, depending on many factors. The time it takes to complete a clinical trial will depend primarily on the disease being targeted and the stage of development for that drug. For example, early-phase trials typically involve fewer participants and shorter durations than later phases.

As you might imagine, there are many variables that affect the length of time required to complete a clinical trial. Here are some common reasons why clinical trials take longer than expected:

  • Drug development is expensive and time-consuming
  • Regulatory agencies also impose strict timelines on how long they allow each phase to take.

Clinical trials are a complicated process that can take years to complete. However, if you are looking for an answer as to how long a clinical trial takes, it is important that you understand what type of clinical trial you want or need.


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