To stop diarrhea fast, effective methods include staying well-hydrated with water and electrolyte drinks, eating bland foods like bananas, rice, applesauce, and toast (the BRAT diet), and using over-the-counter anti- diarrheal medications such as loperamide (Imodium) or bismuth subsalicylate (Pepto-Bismol). These medications help firm up stools by slowing down digestion or reducing intestinal inflammation. However, if diarrhea is caused by an infection, especially with fever or blood in stool, it is important not to use anti-diarrheal drugs without medical advice, as the body needs to clear the infection. Staying hydrated and resting are also crucial for recovery. If symptoms become severe or persist, consult a doctor promptly.