Here is an interesting little discovery
I made when research
ing a project on caffeine
Caffeine restricts (narrows) blood vessels. Headaches are (generally) caused by dilated (widened) blood vessels which applies pressure to your pressure/pain receptors. By consuming caffeine, the caffeine restricts the blood vessels thereby reducing, or even eliminating, the headache. I have verified this fact through personal experience and from my local doctor.
So the next time you have a headache, and you don't have any Panadol on hand, simply look for the nearest coffee or sweet caffeinated beverage and you should have some relief from your pain.
Of course, if pain persists, please see your doctor.
Sorry, couldn't resist using that cliche.