Before human studies
Laboratory and preclinical work explore how an investigational approach behaves and whether available evidence supports testing in people. This work can inform a first clinical protocol, but findings from models do not guarantee results in humans.
Initial safety and dose
Phase 1 studies often involve a relatively small number of participants and focus on safety, tolerability, how the body handles an intervention, and dose. Some enroll healthy volunteers; others enroll people with a specific condition. Potential benefit may be uncertain.
Early evidence and continued safety
Phase 2 studies generally examine whether the intervention shows the intended biological or clinical effect while continuing to gather safety information. Researchers may compare doses or use a control group.
Confirmation at larger scale
Phase 3 studies often include more participants and compare an investigational approach with a placebo, standard care, or another intervention. Results may support regulatory review, but approval is never guaranteed.
Questions after authorization
Post-authorization research can examine longer-term safety, real-world use, additional populations, or comparative outcomes. Approved products can still have uncertainties and study-specific procedures.
Not every study uses phases
Observational studies, behavioral research, diagnostic studies, device studies, and some feasibility or registry projects may not fit the medicine-development phase framework. Ask what type of research is being conducted and which rules govern it.
Read beyond the phase label
Review the intervention, assignment method, control group, visit burden, known risks, unknowns, alternatives, costs, and eligibility criteria. The phase is one part of the picture.
From results to decisions
A single study rarely settles every question. Researchers assess study quality, consistency, effect size, missing data, safety findings, and relevance to different populations. Regulatory authorization and professional guidelines involve broader evidence and separate judgments. Talk with a licensed healthcare professional before making care decisions.