Testing for safety only at first is just following the normal procedure.
> Researchers conduct clinical trials in a series of steps called phases.
Phase I trials: Researchers test a medicine or other treatment in a small group of people for the first time. The purpose is to learn about the best dosage for a medicine or other treatment and to learn about the safety and side effects.
Phase II trials: Researchers study the new medicine or treatment in a larger group of people to determine its effectiveness and to further study its safety.
Phase III trials: Researchers give the new medicine or treatment to an even larger group of participants to confirm its effectiveness, monitor side effects, compare it with standard or similar treatments or a placebo , and collect information that will allow the new medicine or treatment to be used safely.
Phase IV trials: After the U.S. Food and Drug Administration (FDA) approves a medicine or treatment and it is made available to the public, researchers track its safety in the general population, seeking more information about the medicine or treatment’s benefits and optimal use.