Drugs or treatments will pass through several stages of clinical trial before they are approved for widespread use. This is because the best way to find out whether a treatment is safe and effective is to test it in large numbers of people, and to assess it alongside conventional treatments. Clinical trials also help identify potential side effects of a new treatment.
It can take years for a treatment to pass through all the different stages of the clinical trials process, so just because something is described as ‘in clinical trials’, this doesn’t mean it will be available soon or is even safe or effective. There are usually three main phases of a clinical trial.
Initial studies in a handful of people to test whether a treatment seems safe enough to do further tests. Phase 1 studies aren’t designed to measure effectiveness.
This type of study continues to look at safety, whilst testing effectiveness in a small group of people. Results at this stage may be ‘promising’ but are by no means definitive.
The treatment is given to hundreds or thousands of people to measure its effectiveness. Only after Phase 3 has completed can someone apply for a license to market and distribute a medicine.
For more on clinical trials read our guide, I've Got Nothing to Lose By Trying It.