It has been frowned upon to leave a job quickly. When looking at a resume, an HR representative may frown upon an applicant, have a job history that has frequently changed. However, there are times where it is acceptable to leave a job quickly, such as within three months. One of the reasons it would be acceptable is that they are experiencing harassment, or they do not feel safe in the environment.
Safety is always key, and if an employee feels that is comprised, they should leave the job. Another reason would be acceptable is if you found a better job than maybe with a better company and better paying. Before leaving, you can bring it to your job to see if they will match it, but if not, you could leave.