How do I get an emergency prescription while traveling?

While traveling in the U.S.

Find a nearby pharmacy that's in-network with your health insurance.
Call the pharmacy and explain the situation.
Call your home pharmacy and ask them to transfer your medication.
If your home pharmacy won't transfer the prescription, call your primary care provider.

What countries do not require a prescription?

Here it is: Here's what's interesting: although prescriptions are required in most of the rich world, there are plenty of middling-income countries where they aren't, including Portugal, Mexico, Brazil, South Africa, Greece, Turkey, South Korea, Russia, and several others.