The Liver's Work

• The prime headache-causing culprit in wine, as in beer or hard liquor, is alcohol. The secondary culprit is the speed at which the wine drinker drinks. When you drink alcohol, the liver reacts to it, quickly, as a poison. The human body can metabolize -- that is, the liver can break down the alcohol content in -- a glass of wine in about an hour. When the liver does this, it changes the alcohol first into acetaldehyde and then into acetic acid, which is eliminated from the body through the intestines.
  
  

Acetaldehyde

• When you drink wine too fast, the liver can't properly complete the steps of breaking down the alcohol into its components. It sends out acetaldehyde (itself a toxin) directly into the bloodstream in order to make room for more alcohol intake. Acetaldehyde, like other poisons the liver deals with, is made water soluble by the liver's activity.
  
  

Acetaldehyde and Dehydration

• Water-soluble acetaldehyde circulating through the bloodstream permeates all body tissues. Individual cells react to that increased interior pressure by releasing excess water content, "like a sponge under pressure," as Jens Priewe says in his book "Wine: A Practical Guide to Enjoying Your Selection." This is why a bout of heavy drinking will cause sweating and dehydration.
  
  

Water and Headaches

• Waterlogged cells in the brain, however, have nowhere to release their water content. This causes a buildup of pressure, which the wine drinker feels as a headache. Drinking water along with wine during a meal may help prevent headaches, in that water will quench the thirst that you might otherwise satisfy with too much wine. However, once you have drunk too much alcohol too quickly, more water only "hastens its spread through the body," Priewe explains.
  
  

Sulfites and Histamines

• The small amount of the population suffering a genuine allergy to sulfites may also get headaches from wine. White or sweet wines especially may trouble these sufferers, since these wines tend to need more sulfur treatment to keep them fresh than red wines do. Red wines, in turn, have more histamines than other wines, and in sensitive people the body's breakdown of these histamines may cause a dilation of the capillaries, leading to a sensation of pressure and headaches.
  
  

Preventing Headaches

• Moderation is the key to preventing headaches from wine drinking. Respect the time frame your body needs to metabolize alcohol, treat wine as a wonderfully flavorful accent to a meal, and you may find that you are able to enjoy it with few or no unpleasant side effects.