Which medication is generally used for diarrhea relief?

Loperamide, commonly known by its brand name Imodium, is widely recognized for its effectiveness in treating diarrhea. It works by slowing down bowel movements and allowing for more water to be absorbed from the fecal matter, which helps to reduce the frequency of diarrhea episodes and improve consistency. This mechanism of action is particularly beneficial for managing acute nonspecific diarrhea and chronic diarrhea associated with certain conditions.

The other medications listed serve different purposes. Pantoprazole (Protonix) is a proton pump inhibitor that reduces stomach acid production, primarily used for conditions like gastroesophageal reflux disease (GERD). Diphenhydramine (Benadryl) is an antihistamine used to treat allergic reactions, motion sickness, and as a sleep aid, but it doesn't address diarrhea. Levothyroxine (Synthroid) is a thyroid hormone replacement used in the treatment of hypothyroidism and has no role in managing gastrointestinal symptoms.

Thus, loperamide is the appropriate choice for diarrhea relief due to its specific action related to slowing intestinal transit.