Alcohol, which is consumed in beverages such as liquor, wine and beer, is a chemical called ethanol. Ethanol may cause headaches by several means.

First, it is a direct vasodilator; in some individuals vasodilation may cause a headache.

Second, ethanol is a natural diuretic; this leads to excretion of salt, vitamins and minerals from the body through the kidneys.

Excess consumption of ethanol may produce dehydration and chemical imbalances in the body.

 Except in “moonshine,” we consume ethanol in beverages that contain other chemicals. These chemicals are called congeners. Congeners impart the specific tastes and flavors that make each beverage unique.

Headaches may occur shortly following consumption of alcohol or the next morning, with the infamous 'hangover.' Those occurring shortly after tend to indicate specific alcohol sensitivity and are more likely to occur in people who already experience migraines or other such headaches.

Cluster headaches, in particular, are triggered by alcohol. For some people, it is the precise type of alcoholic drink that causes a headache. A person may experience a headache from one glass of wine but find that he or she can drink several shots of vodka without suffering from a headache. Even within wines, for example, some may find that a glass of white wine causes no problem yet red wine leaves them with an excruciating migraine. Red wine contains tyramine, which is a known migraine trigger and so avoidance of red wine may be necessary for some people.

These congeners also have a variety of effects that can cause headaches, alter other chemicals in the body, and induce the hangover effect if consumed in excess. Fructose, the naturally occurring sugar from fruits, helps return portions of the body’s chemical balance back to normal following ethanol consumption.

You are the one to decide how much alcohol you can safely consume before you suffer from a headache. You may need to make a note of which drinks seem to trigger your migraines or other headaches. If you are fortunate enough to normally be headache-free, taking a little extra care before, during and after drinking by eating a balanced meal, drinking sufficient fluids and avoiding excessive amounts of alcohol can help prevent a hangover headache the next day. With a little extra effort in looking after yourself, you should be able to enjoy a few drinks and your body will thank you the next day. You'll feel better for it and can avoid those painful headaches.

Be extremely cautious the next day if taking any painkillers for your headache, as alcohol still in your system combined with painkillers such as acetaminophen can have dangerous effects. Be sure to drink water to combat the dehydration caused by the alcohol. Many people drink coffee the next morning but as coffee it also a diuretic, this will only increase your dehydration and may also further upset your stomach and intensify your headache.