This would depend on the situation. If you are talking with your friend(s) about digestive problem then there is nothing wrong with saying this word. You would want to avoid saying this word out-loud in a formal or food-related venue, such as a restaurant or formal/professional (work) gathering without using some discretion. The word itself is not profane by any means; however, its usage in a restaurant or professional situation may conjure mental images that people around you may prefer not to imagine!

I would use this word with a medical professional, but not in normal conversation. Just as I would talk to my doctor about eczema/hypertension/genitals, but use 'normal' language elsewhere , I would describe diarrhœa (sorry, I'm English) to my friends and family using something non-medical: the runs, the trots, the drizzle shits. I would avoid mentioning it directly to somebody in a formal situation, e.g. a customer, maybe I'd say I had a digestive problem.

In a social situation you might use in stead: An upset stomach. It's less visual :)