If this problem happens rarely you should take Immodium or another anti-diarrhea medication. If this is happening a lot for more than one day you should go to a doctor. Tell your doctor about your frequent diarrhea and he will be able to tell you what is going on with your bowel.
Keep both a food log and a log of your bowel movements. This will let you find out what foods are causing the diarrhea so you will know what foods to stay away from. It might be lactose intolarance, which affects lots of adults.
Most important is drinking a lot of water to replenish lost liquids in your body. Staple foods also help to stop diarrhea, foods such as bananas, rice and toast. If it continues indefinitely, you should go to hospital to have an IV put in to replenish vitamins that were lost.
Frequent diarrhea could be caused by a number of things. One thing that causes it is too many soft drinks. Try reducing your intake, and see if it helps.