If the diarrhea is not very severe and is only acute diarrhea then the acute diarrhea should only last at most of 2 to 3 days before going away.
If the diarrhea is more severe then the diarrhea may last up to a week and if the diarrhea lasts longer than a week you should see a doctor or go to urgent care to help get the diarrhea stopped because having too much diarrhea can cause dehydration and cause loss of electrolytes.
When you do have diarrhea try drinking some water to stay hydrated and even drink some Pedialyte to help replace lost electrolytes that occurs when you have too much diarrhea.