Medically reviewed by Drugs.com. Last updated on Dec 6, 2021.
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, frequent hangovers are 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 up to 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 content 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 and how much you drank, you may notice:
- Fatigue and weakness
- Excessive thirst and dry mouth
- Headaches and muscle aches
- Nausea, vomiting or stomach pain
- Poor or decreased sleep
- Increased sensitivity to light and sound
- Dizziness or a sense of the room spinning
- Decreased ability to concentrate
- Mood disturbances, such as depression, anxiety and irritability
- Rapid heartbeat
When to see a doctor
Hangovers after a single night's drinking go away on their own. Talk with your doctor if you're concerned that frequent, heavy drinking may lead to serious alcohol withdrawal, or when regular hangovers affect your quality of life, including your personal relationships or your performance at work. Treatment for alcohol problems is widely available.
When it's an emergency
More-severe signs and symptoms that accompany heavy drinking may indicate alcohol poisoning — a life-threatening emergency. Call 911 or your local emergency number if a person who has been drinking shows signs of:
- Slow breathing (less than eight breaths a minute)
- Irregular breathing (a gap of more than 10 seconds between breaths)
- Blue-tinged skin or pale skin
- Low body temperature (hypothermia)
- Difficulty remaining conscious
- Passing out (unconsciousness) and can't be awakened
A person who is unconscious or can't be awakened is at risk of dying. If you suspect that someone has alcohol poisoning — even if you don't see the classic signs and symptoms — seek immediate medical care.
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.
Various factors may contribute to a hangover. For example:
- Alcohol causes your body to produce more urine. In turn, urinating more than usual can lead to dehydration — often indicated by thirst, dizziness and lightheadedness.
- Alcohol triggers an inflammatory response from your immune system. Your immune system may trigger certain agents that commonly produce physical 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. Alcohol 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, mood disturbances and even seizures.
- Alcohol causes your blood vessels to expand, which can lead to headaches.
- Alcohol can make you sleepy, but it prevents deeper stages of sleep and often causes awakening in the middle of the night. This may leave you groggy and tired.
Alcoholic beverages contain ingredients called congeners, which give many types of alcoholic beverages their flavor and can contribute to hangovers. Congeners are found in larger amounts in dark liquors, such as brandy and bourbon, than in clear liquors, such as vodka and gin.
Congeners are more likely to produce a hangover or increase the severity of a hangover. But drinking too much alcohol of any color can still make you feel bad the next morning.
Anyone who drinks alcohol can experience a hangover, but some people are more susceptible to hangovers than others are. 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.
Factors that may make a hangover more likely or severe include:
- Drinking on an empty stomach. Having no food in your stomach speeds the body's absorption of alcohol.
- Using other drugs, such as nicotine, along with alcohol. Smoking combined with drinking appears to increase the likelihood of next-day misery.
- Not sleeping well or long enough after drinking. Some researchers believe that some hangover symptoms are often due, at least in part, to the poor-quality and short 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 and may be more likely to produce a hangover.
When you have a hangover, you're likely to experience problems with:
Not surprisingly, this temporary dulling of your abilities increases your risk of a number of problems at school or work, such as:
- Trouble completing tasks
- Conflict with others
- Falling asleep at school or on the job
- Workplace injuries
Despite various over-the-counter pills and tablets that claim to prevent hangovers, the only guaranteed way to prevent a hangover is to avoid alcohol. If you choose to drink, do so in moderation.
Moderate alcohol use for healthy adults means up to one drink a day for women of all ages and men older than age 65, and up to two drinks a day for men age 65 and younger.
The less alcohol you drink, the less likely you are to have a hangover. It may help to:
- Eat before and while drinking. As alcohol is absorbed more quickly if your stomach is empty, it may help to eat something before drinking alcohol and during the time you're drinking.
- Choose carefully. Beverages with fewer congeners are slightly less likely to cause hangovers than beverages with more congeners, but remember that all types of alcohol can result in a hangover.
- Sip water between drinks. Drinking a full glass of water after each alcoholic drink will help you stay hydrated. It'll also help you drink less alcohol.
- Know your limits and only drink in moderation. Decide ahead of time how many drinks you'll have — and stick to it. Don't feel pressured to drink.
- Take it slow. Avoid having more than one alcoholic drink in an hour. Stop drinking completely when you've reached your limit (or before then).
Some people take over-the-counter pain relievers, such as aspirin or ibuprofen (Advil, Motrin IB, others), to prevent hangover symptoms. But ask your doctor if this is safe for you and what dosage is best for you. These medications may interact with other medications, and acetaminophen (Tylenol, others) may cause liver damage if too much alcohol is consumed.
Time is the only sure cure for a hangover. In the meantime, here are a few things you can do to help yourself feel better:
- Fill your water bottle. Sip water or fruit juice to prevent dehydration. Resist any temptation to treat your hangover with more alcohol. It'll only make you feel worse.
- Have a snack. Bland foods, such as toast and crackers, may boost your blood sugar and settle your stomach. Bouillon soup can help replace lost salt and potassium.
- Take a pain reliever. A standard dose of an over-the-counter pain reliever may ease your headache. But aspirin can irritate your stomach. And if you regularly drink alcohol to excess, acetaminophen (Tylenol, others) can cause severe liver damage even in doses previously thought to be safe.
- Go back to bed. If you sleep long enough, your hangover may be gone when you awaken.
Proposed alternative remedies for hangovers abound, but studies haven't found any natural remedies that consistently improve hangover symptoms.
Talk with your doctor before trying any alternative medicine. Keep in mind that natural doesn't always mean safe. Your doctor can help you understand possible risks and benefits before you try a treatment.