Eli5: Why is caffeine often recommended for headache relief?

Question

Eli5: Why is caffeine often recommended for headache relief?

In: 418

Answer 1

Many headaches caused by your blood vessels expanding and creating pressure in your head. Caffiene make the blood vessels shrink, reduces the headache. Other things that might help, drinking water. But especially if the headache is from caffeine withdrawal, caffeine helps.

Edit: typed headache twice instead of caffiene