[flangola7]

Epinephrine increases the strength of painkillers. That's why there's caffeine in Excedrin.

[freedomben]

I thought the caffeine was there to restrict/narrow blood vessels which usually helps with migraines. Multi-purpose maybe?

[cjbgkagh]

AFAIK, I think it depends on where in the body, vasoconstriction in the head vasodilation for the rest of the body.

[etskinner]

What does epinephrine have to do with caffeine?

[cloudwalk9]

Caffeine directly kickstarts the adrenal glands