Medical effects of caffeine on headaches

Here is an interesting little discovery I made when researching 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.

Of course, as with any drug, caffeine consumption over a prolonged period of time induces a physiological dependence. Because of this, the effects of caffeine on the blood vessels will not be detectable whenever you drink coffee. So, if you regularly drink caffeine, it will not have the desired effect on your headaches. Once regularly consuming caffeine, your veins will be at their "usual" width, so long as your intake of caffeine continues. To get the desired constriction, you must consume a much larger dose.

However, also due to the effects of addiction (or if you will, the effects of withdrawal), once you stop consuming caffeine regularly, the reverse effects of the drug take place. Thus, when you stop consuming caffeine, the blood vessels dilate. This causes headaches, as tobtoh mentioned. This is, in fact, the reason that people on "reahbilitation" from caffeine experience headaches for several days after quitting.

At the end of every exam period I stop drinking coffee and other caffeinated products for a couple of weeks, to clean my body. I always have some pain reducing capsules nearby for the first few days. I also keep anti-depressant drugs nearby, but that's another story.