Early Phase 1
Initial studies to determine safety, dosage range, and side effects in a very small number of participants. Sometimes called "Phase 0" trials.
Phase 1
Tests a new treatment in a small group (20–80 people) to evaluate safety, determine safe dosage ranges, and identify side effects.
Phase 2
Treatment given to a larger group (100–300 people) to see if it's effective and to further evaluate its safety.
Phase 3
Treatment given to large groups (1,000–3,000 people) to confirm effectiveness, monitor side effects, compare to commonly used treatments, and collect information for safe usage.
Phase 4
Post-marketing studies after a treatment has been approved for use, providing additional information about risks, benefits, and optimal use.
Other / Not Applicable
Trials that don't fit into standard phase categories, including observational studies that don't test interventions or expanded access programs.
