What are the different kinds of clinical trials?

Clinical trials are categorized in four phases:

Phase 1 clinical trials involve relatively small groups of patients (15 to 30). They help determine maximum safe dosages of new drugs, which have gone through laboratory testing. These trials closely monitor patients for side effects and organ function. Phase 1 trials also help determine the best way to administer a new treatment.

Phase 2 trials, once drug safety has been established, involve larger groups of patients (usually less than 100) to monitor the response of tumors to the treatment that’s under study. This phase further checks for safety.

Phase 3 trials often include thousands of patients to confirm previous findings and determine effectiveness over a wide range of people.

Phase 4 clinical trials are used to follow drugs and treatments after they gain FDA approval and go on the market.