A hangover is a group of unpleasant signs and symptoms that can develop after drinking too much alcohol. As if feeling awful weren't bad enough, hangover is also associated with poor performance and conflict at work.

What is it?

  • A hangover is a group of unpleasant signs and symptoms that can develop after drinking too much alcohol. As if feeling awful weren't bad enough, hangover is also associated with poor performance and conflict at work.
  • As a general rule, the more alcohol you drink, the more likely you are to have a hangover the next day. But there's no magic formula to tell you how much you can safely drink and still avoid a hangover.
  • However unpleasant, most hangovers go away on their own, though they can last longer than 24 hours. If you choose to drink alcohol, doing so responsibly can help you avoid future hangovers.


Hangover symptoms typically begin when your blood alcohol drops significantly and is at or near zero. They're usually in full effect the morning after a night of heavy drinking.

Depending on what you drank and how much you drank, you may notice:

  • Fatigue
  • Thirst
  • Headaches and muscle aches
  • Nausea, vomiting or stomach pain
  • Poor or decreased sleep
  • Sensitivity to light and sound
  • Dizziness or a sense of the room spinning
  • Rapid heartbeat
  • Bloodshot eyes
  • Shakiness
  • Decreased ability to concentrate
  • Mood disturbances, such as depression, anxiety and irritability


Hangovers are caused by drinking too much alcohol.

A single alcoholic drink is enough to trigger a hangover for some people, while others may drink heavily and escape a hangover entirely. In general, however, more than three to five alcoholic drinks for a woman and over five to six for a man will usually result in a hangover.

Various factors may contribute to the problem. For example:

  • Alcohol stimulates your body to produce more urine. In turn, urinating more than usual can lead to dehydration — often characterized by thirst, dizziness and lightheadedness.
  • Alcohol triggers an inflammatory response from your immune system. In particular, your immune system may trigger certain agents that commonly produce symptoms such as an inability to concentrate, memory problems, decreased appetite and loss of interest in usual activities.
  • Alcohol irritates the lining of your stomach, increases the production of stomach acid and delays stomach emptying. Any of these factors can cause abdominal pain, nausea or vomiting.
  • Alcohol can cause your blood sugar to fall. If your blood sugar dips too low, you may experience fatigue, weakness, shakiness and mood disturbances.
  • Alcohol causes your blood vessels to expand, which can lead to headaches.
  • Alcohol can make you sleepy — but your quality of sleep will decrease. This may leave you groggy and fatigued.
  • Alcoholic beverages contain ingredients called congeners — which give many types of alcoholic beverages their flavor and which can contribute to hangovers. Congeners are found in larger amounts in dark liquors, such as brandy and whiskey, than in clear liquors, such as vodka and gin.

Risk factors

Anyone who drinks alcohol can experience a hangover, but some people are more susceptible to hangovers than are others. A genetic variation that affects the way alcohol is metabolized may make some people flush, sweat or become ill after drinking even a small amount of alcohol.

Research hasn't clearly shown whether light drinkers or heavy drinkers are more likely to experience hangovers. Some evidence suggests that frequent drinkers may build up a tolerance that decreases their risk of hangovers.

Factors that may make a hangover more likely or severe include:

  • Drinking on an empty stomach. Having food in your stomach slows the body's absorption of alcohol.
  • Using other drugs, such as nicotine, along with alcohol. Smoking and drinking together appears to increase the likelihood of next-day misery.
  • Not sleeping long or well enough after drinking. Some researchers believe that some hangover symptoms are often due, at least in part, to the short and poor-quality sleep cycle that typically follows a night of drinking.
  • Having a family history of alcoholism. Having close relatives with a history of alcoholism may suggest an inherited problem with the way your body processes alcohol.
  • Drinking darker colored alcoholic beverages. Darker colored drinks often contain a high volume of congeners — the chemicals used to add color and flavor to alcohol. Congeners are more likely to produce a hangover.

Drinks with a high congener content include:

  • Bourbon
  • Scotch
  • Tequila
  • Brandy
  • Dark-colored beers and beer with high alcohol content
  • Red wine

By comparison, drinks with a lower congener content — such as lighter-colored beers, gin and vodka — are less likely to cause a hangover. However, while lighter colored drinks may slightly help with hangover prevention, drinking too many alcoholic beverages of any color will still make you feel bad the morning after.


When you have a hangover, you're likely to experience problems with your:

  • Memory
  • Concentration
  • Dexterity
  • Visual-spatial skills, or your ability to accurately perceive how objects you're looking at relate to each other in space around you

Not surprisingly, this temporary dulling of your abilities increases your risk of a number of problems at work, including:

  • Trouble completing your tasks
  • Criticism from a supervisor
  • Conflict with co-workers
  • Falling asleep on the job
  • Workplace injuries