Diarrhea Say: dy-uh-ree-uh If you've ever had a bad time in the bathroom, then you know what this is. Diarrhea happens when there's too much water in your bowel movements. With diarrhea, you have to go to the bathroom a lot and your poop is runny and watery. Back to Articles Related Articles Note: All information is for educational purposes only. For specific medical advice, diagnoses, and treatment, consult your doctor. © 1995-2021 KidsHealth®. All rights reserved. Images provided by The Nemours Foundation, iStock, Getty Images, Veer, Shutterstock, and Clipart.com.