You have an iron constitution. You never get sick. You’ve eaten street food from Calcutta to La Paz. In other words, you think you’re invincible. But, eventually, we all get sick. Most of the time, seeing a doctor will be pretty simple and you can address the problem with an expert. Other times, however, you’ll be stuck on a plane, a remote island or have no idea how to say “hospital” in the native language. That’s when you’ll be glad that you packed an antibiotic.

Whenever I’m traveling to a place with dodgy drinking water and an abundance of alluring street markets (those traits always seem to overlap), I have my doctor write me a prescription for Ciprofloxacin (or, as the kids are calling it, Cipro) which I fill before hitting the road. In the rare moment when your stomach gurgles and your poop resembles frozen yogurt, you’ll be glad that you can start killing whatever bug has begun Couchsurfing in your GI tract.

Persistent illnesses should be treated by a doctor and you shouldn’t start popping antibiotics every time your head hurts or tummy aches. But it’s always best to have some meds at the ready for when the shit hits the fan underpants.