A phase 1 clinical trial is the first phase of the trial phase that involves people. Prior to starting phase one, a drug has to be shown to be safe and effective in the laboratory and animals. When a phase 1 clinical trial begins, researchers will try to find the highest dose of a drug that can be given without causing severe side effects. Typically, this type of clinical trial begins by giving everyone in the trial a low dose. Then, over time, the dose is increased to see if severe side effects begin. The main concern of a phase 1 clinical trial is safety. Everyone is watched closely to see if they develop side effects. Phase 1 trials are usually small, so severe side effects may not be detected until later in the research process.