Graduated therapy. I'm a believer in *treating* travelers diarrhea (td), which is common & often bacterial. Mild symptoms can be controlled with otc Imodium (loperamide) (anti-diarrheal) & hydration. More acute symptoms can be treated with the addition of a short course (one day!) of an antibiotic, usually ciprofloxacin. Some regions (se asia) have Cipro resistance -> azithro or rifaximin. Consult your travel medicine provider!
Destination specific. Traveler's diarrhea is a bacterial diarrhea transmitted in water and food. Different countries have different bacteria with different susceptibility to antibiotics. The symptoms of diarrhea can be treated with loperamide, but the bacterial cause has several different antibiotics recommended. Talk with your travel medicine specialist to get up-to-date advice.