Hangover Symptoms

“Hangover” is the term used to describe the group of symptoms that occur after having drunk too much alcohol. In most cases, the more alcohol a person drinks, the more likely they are to suffer from a hangover once the effects of alcohol have worn off.

Image Credit: Dragana Gordic / Shutterstock
Image Credit: Dragana Gordic / Shutterstock

The symptoms of a hangover usually start once the blood alcohol level drops significantly or reaches zero and the intoxicating effects of alcohol can no longer be felt. Depending on how much alcohol a person has drunk, some of the symptoms they may experience include the following:

  • Nausea
  • Muscle ache
  • Headache
  • Thirst
  • Lethargy
  • Stomach upset
  • Diarrhea
  • Oversensitivity to light and sound
  • Anxiety
  • Depression
  • Poor concentration
  • Feelings of irritability

Causes of symptoms


The main cause of hangover symptoms is dehydration. Alcohol is a diuretic and triggers the body to shed water through urination. Frequent urination can lead to dehydration and result in symptoms such as headache, fatigue, and a dry mouth.

Toxin intake

Ethanol is a toxic chemical that, once absorbed into the bloodstream, circulates around the body causing cell damage. Furthermore, a by-product of alcohol metabolism called acetaldehyde accumulates in the body, causing vomiting and headaches. Alcohol fermentation also produces toxins called congeners, which are the chemicals that give alcoholic drinks their flavor. Congeners cause irritation to blood vessels and brain tissue, which worsens hangover symptoms.


Drinking too much alcohol causes the blood glucose level to drop (hypoglycemia). It breaks down glycogen, the glucose store in the liver. Once the liver stores of glycogen are depleted, hypoglycemia develops. Certain hypoglycemia symptoms result from a lack of glucose supply to the brain, while others occur in response to the body’s release of epinephrine in order to help increase blood glucose. Epinephrine release can lead to shakiness, weakness, fast heart rate, and hunger. A lack of glucose in the brain can affect concentration, vision, speech, and coordination, as well as causing headaches and light-headedness. Hypoglycemia can also affect emotions and lead to irritability, aggressiveness, and crying.

Disrupted sleep

Alcohol stops the production of an amino acid called glutamine, which can act as a stimulant and play a role in wakefulness. Once a person has stopped drinking, the body responds to the lack of glutamine by producing an excess of the substance. This interferes with normal sleep, which can cause tiredness.


Withdrawing from alcohol leads to tremors and sweating, since the brain adapts to alcohol, even if a person has only drunk for one evening. The brain is then in a withdrawal state once alcohol levels in the body fall. This leads some people to opt for “hair of the dog,” which refers to consuming more alcohol to take the edge off withdrawal symptoms.

Stomach irritation

Acid production is increased in the stomach when alcohol is consumed. This aggravates the stomach lining and delays the stomach’s emptying process, which can result in pain and vomiting.

Duration of Hangover Symptoms

Hangovers can last for as long as three days, although they usually pass more quickly. How long the symptoms last depends on a number of factors including how much was drunk, the extent of dehydration, gender, liver health, the use of certain drugs, and nutritional status.

Symptom Relief

Some measures people can take to relieve hangover symptoms include the following:

  • Rehydrating the body by drinking water; non-fizzy, soft drinks; or isotonic drinks
  • Topping up nutrition levels by eating food rich in minerals and vitamins
  • Taking over-the-counter pain killers to alleviate any painful symptoms such as headache
  • Increasing blood sugar level by eating glucose-rich foods
  • Staying in bed and sleeping while the hangover passes

Further Reading

Last Updated: Dec 29, 2022

Sally Robertson

Written by

Sally Robertson

Sally first developed an interest in medical communications when she took on the role of Journal Development Editor for BioMed Central (BMC), after having graduated with a degree in biomedical science from Greenwich University.


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