How many phases of a clinical trial are there? 

Clinical trial phases

There are typically four main phases of a clinical trial plus the ‘Preclinical’ stage which refers to cell and animal studies. You will be informed of which phase your chosen clinical trial is prior to committing. 

  • Phase I studies focus on evaluating safety and how the drug interacts with the human body. 
  • Phase II studies focus on evaluating safety, side effects, measures effectiveness and dosage. 
  • Phase III studies confirm effectiveness and monitor safety. 
  • Phase IV studies are conducted after a drug has been approved to gather information on side effects in long term use.