An Overview of Hangover

The "morning after" effects of alcohol

A hangover is a common condition that occurs hours after alcohol consumption. You may feel headachy, nauseated, or dizzy when you have a hangover. The effects usually begin hours after drinking alcohol and can last for a whole morning, or even for several days.

Hangovers tend to occur after heavy alcohol consumption. But you can have symptoms after consuming just one or two drinks the night before, while other times you might not experience a hangover even after consuming large amounts of alcohol. While there are differences in how people experience hangovers, these differences are not understood and are not related to resilience or alcohol tolerance.

In general, a hangover is highly unpleasant, but not dangerous. While they generally resolve on their own after several hours, there are some strategies for managing a hangover.

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Hangover Symptoms

The medical term for a hangover is veisalgia, which is a combination of the Greek word for pain and a Norwegian word for "uneasiness following debauchery."

There are several recognizable effects of a hangover. Because drinking is often an evening activity, hangovers are commonly described as "morning-after" effects. However, you can have a hangover any time of the day—they usually begin between three and ten hours after drinking.

Common symptoms of a hangover include:

  • A headache
  • Feeling run down
  • Poor sense of overall well-being
  • Photophobia (aversion to light)
  • Phonophobia (increased sensitivity to sound)
  • Aching throughout the body
  • Diarrhea
  • Loss of appetite
  • Shaking or trembling
  • Fatigue
  • Nausea and vomiting

You may notice these effects after you drink alcohol and then sleep for a few hours. Generally, hangovers are characterized by discomfort—and you may want to stay in bed all day. Sometimes, hangovers can be more serious and can cause health issues that require medical attention.

Less common effects of a hangover that may need medical care include:

  • Brain fog (trouble thinking)
  • Dizziness (especially after standing up)
  • Clumsiness
  • Tachycardia (rapid pulse and heart rate)
  • Hypotension (low blood pressure)
  • Hemoptysis (coughing blood) or hematemesis (vomiting blood)

These effects can begin while you are still drinking, and can last for longer than the typical effects of a hangover. Without medical treatment, you could fall, lose consciousness, or develop health complications due to these delayed effects of alcohol.


There are several factors that contribute to a hangover. Alcohol has temporary and long term effects on the body. The temporary effects include immediate and delayed effects—a hangover is caused by the delayed effects of alcohol.

While there are slight differences in how quickly or slowly different people metabolize alcohol, the physiology of a hangover is very similar between one person and another.

Causes of a hangover include:

  • Dehydration: Alcohol inhibits the kidney's reabsorption of water, causing loss of fluid in the urine.
  • Vascular changes: Alcohol induces vasodilation (widening and relaxation of the blood vessels).
  • Neurotransmitter alterations: Alcohol increases the action of gamma-aminobutyric acid (GABA), a neurotransmitter in the brain that slows down brain activity.
  • Hormonal effects: Alcohol modulates antidiuretic hormone (ADH), a hormone that stimulates the kidneys to absorb fluid.
  • Alcohol toxicity: Different alcohol additives and metabolites can be difficult for the body to metabolize and may be toxic.
  • Alcohol withdrawal: In addition to alcohol's direct effects, alcohol withdrawal can also cause effects that contribute to a hangover.
  • Effects on the liver: Alcohol consumption can have an immediate effect on your liver. The liver is involved in metabolizing most nutrients, detoxifying the body, and activating several vitamins. When the liver is impaired, you can develop digestive symptoms, low energy, and cognitive (thinking) problems.

With alcohol ingestion, the effects on the liver are generally long term effects that are not noticeable until years of liver damage have caused liver failure. In some instances, however, delayed short term effects can be symptomatic.

The combination of these physiologic effects of alcohol can cause several of the symptoms of a hangover.

Headaches, for example, are triggered by alcohol's vascular changes in the brain and by dehydration. Dizziness is exacerbated by alcohol toxicity, as well as by dehydration. Fatigue and muscle aches are caused by alcohol withdrawal and dehydration, and the gastrointestinal (GI) symptoms are mediated by alcohol's direct action on the GI system, as well as the hormonal and neurotransmitter alterations.

Severe Effects

It is not completely clear why a hangover can be associated with problems like hypotension and tachycardia. Dehydration and electrolyte abnormalities can lead to these effects, but other factors, such as alcohol toxicity, may contribute as well.

Drunk vs. Hangover

You don't necessarily have to have been drunk to have a hangover, and there are differences between being drunk and having a hangover. Most people experience a lack of inhibition (decreased social filter or appropriate boundaries), diminished coordination, and slow reaction time when drunk. The alcohol-associated increase in the action of GABA contributes to these effects.

When you have a hangover, pain and discomfort are prominent, while the behavioral changes associated with drunkenness are not usually still present.

In some instances, symptoms of a hangover can begin before the effects of alcohol have worn off. This is usually the result of very heavy alcohol intake or metabolic issues (such as liver or kidney failure).


There is no cure for a hangover, but there are some treatment strategies . Waiting is typically the most common way of dealing with hangovers because they tend to resolve on their own. However, you may not want to sleep all day—or you may have to go to work or school.

There are treatment approaches that can relieve some of the severe effects of a hangover. In addition to getting some rest, you can drink fluids, eat in moderation, and take over the counter (OTC) medications as well.

  • Hydration: It is important to stay hydrated. If you can drink fluids before you drink alcohol and before you go to sleep after a night of drinking, you may be able to avoid a hangover. When you wake up, be sure to sip on fluids, which can include non-caffeinated beverages like water, ginger ale, or electrolyte drinks.
  • Eating: If you can eat a bit of bland food, like crackers or other carbohydrates along with alcohol or even after you drink, it can help prevent your GI symptoms.
  • OTC medications: Pain medications such as Advil (ibuprofen) can help relieve headaches and aches and pains. OTC anti-nausea medications can relieve your stomach upset.

Because alcohol affects the liver, and Tylenol (acetaminophen) is metabolized by the liver, it is not recommended to take acetaminophen or medications that contain acetaminophen during a hangover.

If you still feel light-headed, have diminished coordination, or if you have a rapid heart rate or a weak pulse, you should seek medical attention. Often, intravenous (IV) fluids can help alleviate the symptoms. But sometimes severe issues, such as vomiting or coughing blood need to be addressed with more intensive medical attention.

A Word From Verywell

Hangovers are not usually dangerous, but they can cause major health issues, especially if you are not in good health to begin with. When it comes to hangovers, some folks have their own favorite hangover "cures." In most cases, they're just personal preferences and the best advice is to stay hydrated, get something to eat, and take it easy.

If you or a loved one has a chronic drinking problem, it is important that you seek professional help. Alcohol abuse can cause health problems, as well as social, interpersonal, and work issues.

4 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  2. van Schrojenstein Lantman M, van de Loo AJAE, Mackus M, Kraneveld AD, Brookhuis KA, Garssen J, Verster JC. Susceptibility to Alcohol Hangovers: Not Just a Matter of Being Resilient. Alcohol Alcohol. 2018 May 1;53(3):241-244. doi: 10.1093/alcalc/agx107.

  3. Mackus M, van de Loo AJAE, Raasveld SJ, Hogewoning A, Sastre Toraño J, Flesch FM et al. Biomarkers of the alcohol hangover state: Ethyl glucuronide (EtG) and ethyl sulfate (EtS). Hum Psychopharmacol. 2017 Sep;32(5). doi: 10.1002/hup.2624. Epub 2017 Jul 6.

  4. Jayawardena R, Thejani T, Ranasinghe P, Fernando D, Verster JC. Interventions for treatment and/or prevention of alcohol hangover: Systematic review. Hum Psychopharmacol. 2017 Sep;32(5). doi: 10.1002/hup.2600. Epub 2017 May 31.

Additional Reading

By Rod Brouhard, EMT-P
Rod Brouhard is an emergency medical technician paramedic (EMT-P), journalist, educator, and advocate for emergency medical service providers and patients.