A hangover is an unpleasant consequence of heavy alcohol consumption and includes a headache and other symptoms. But even moderate amounts of alcohol can induce headaches even in the absence of a hangover in some people. A headache may begin within a few hours after drinking alcohol-containing beverages or can start up to 16 hours later. Several biological effects of alcohol are responsible for causing headaches in susceptible individuals.
Body Fluids and Blood Pressure
According to the National Headache Foundation, the ethanol component of alcoholic beverages may cause the body to lose fluid. Dehydration, a change in the balance of body water and essential nutrients, results. This affects the fluids surrounding the brain and decreases the blood pressure and blood flow to the brain. In addition, alcohol-containing drinks can decrease blood pressure in the brain by widening the blood vessels that supply the brain. These changes can produce pain and sensitivity, resulting in a headache.
A variety of chemicals can contribute to post-alcohol headaches. Studies have documented measurable changes in the immune system and in a number of different chemicals -- including cogeners, flavonoids, tryptamines and acetaldehydes -- that might have a connection with headaches. The exact mechanism of the headache-producing qualities of these chemicals is not fully understood.
Not everyone is prone to alcohol-induced headaches. Typically, people who experience headaches after drinking wine, beer, spirits or mixed drinks tend to notice the unpleasant correlation and avoid them. A study published in the March 2012 "Journal of Headache Pain" noted that people who develop redness of the cheeks after drinking alcohol tend to have a higher incidence of alcohol headaches as well. People who are prone to migraine headaches are also susceptible to headaches from drinking alcohol. Women are more likely than men to experience headaches after drinking alcoholic beverages.
Red wine is often blamed for headaches, and there is possibly a stronger correlation between headaches and red wine than other types of alcohol. However, a preference or aversion to a specific drink is based on personal experiences and observations.
While alcohol can cause headaches due to the biological responses to chemicals in the alcohol, there may also be a correlation with stress. A negative mood before drinking alcohol can predispose some people to migraine headaches independent of what they drink.