I think people tend to load up on way more OTC medicines than are necessary, namely anti-diarrheals (loperamide), which may cause more harm than good. Your GI tract responds to infectious pathogens by clearing them out (diarrhea), in which case if you stop the diarrhea, you prevent your body from ridding itself of the pathogen. It's better to increase fluid replacement (electrolyte solutions) and get some rest. Most cases clear up within a few days and are likely viral. If it lasts longer or the severity is such that dehydration is a big problem, you need medical attention - in which case an anti-diarrheal may be necessary, if, and only if, medical care is not immediately available.

Most people I know are too quick to pop open XYZ OTC drug to control symptoms for whatever's ailing them, when increasing fluids and simply getting some rest will help them recover quicker. Of course this speaks to our fast-paced, cannot-be-bothered-by-illness lifestyles