Dehydration occurs when the body does not have sufficient amounts of fluid to function effectively. This can cause symptoms such as headache, dizziness, and fatigue. Alcohol has a dehydrating effect on the body, especially when a person consumes it in large quantities.

Severe and untreated dehydration can be life threatening.

Understanding how alcohol affects fluid and electrolyte levels in the body is important for preventing dehydration and maintaining health.

In this article, we describe how alcohol dehydrates the body and provide tips on how to counteract dehydration due to alcohol consumption. We also outline some additional causes of dehydration.

Dehydration is when the body does not have sufficient amounts of fluid to function effectively. This happens when a person loses more fluids than they take in.

Dehydration can result from using diuretics. These are substances that promote urine production, or diuresis. Alcohol is a diuretic and can therefore cause dehydration.

Dehydration can affect multiple bodily functions and cause a wide range of symptoms.

Mild symptoms include:

Moderate to severe symptoms include:

Without treatment, severe dehydration can cause serious complications, such as:

  • electrolyte imbalances
  • kidney problems
  • shock
  • coma
  • death

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Alcohol is a diuretic and therefore causes excessive urination. As a result, a person loses vital fluids and electrolytes.

Some factors that play a role in alcohol-induced dehydration include:

  • Drinking alcohol on an empty stomach: Alcohol enters the bloodstream via blood vessels in the tissue lining of the stomach and small intestine. Without food in the stomach, alcohol goes straight into the bloodstream instead of being absorbed more slowly through the stomach and small intestine. As such, drinking on an empty stomach can contribute to dehydration.
  • Appetite suppression: Large quantities of alcohol can suppress appetite, making a person less likely to eat while drinking. This in turn can speed up alcohol absorption and associated dehydration.
  • Kidney function: Drinking alcohol decreases the ability of the kidneys to filter the blood and maintain the balance of fluids and electrolytes in the body. Alcohol also suppresses the release of the antidiuretic hormone vasopressin, which controls how much water the kidneys reabsorb and retain. This reduces fluid retention and increases urination.

The risk of dehydration is greater in older adults and people with chronic conditions, such as:

To stay hydrated, a person needs to take steps before, during, and after alcohol consumption.

Below are some tips that can help prevent alcohol-induced dehydration:

  • Consume alcohol in moderation: The Centers for Disease Control and Prevention (CDC) advise that males drink a maximum of two drinks per day and that females have no more than one drink per day.
  • Drink alcohol slowly: It takes the liver 1 hour to process each serving of alcohol.
  • Drink water while drinking alcohol: It is advisable to have at least 1 glass of water for each serving of alcohol.
  • Drink water regularly: People who forget to drink water regularly can try the following:
    • carrying water in a bottle with them
    • drinking water on a schedule
    • using an app to track their fluid consumption
  • Drink other hydrating beverages: In addition to water, a person can consume other hydrating beverages, such as:
  • Avoid sugary and caffeinated beverages: These can promote dehydration.
  • Eat hydrating foods: Examples of foods with high water content include:
    • fruits
    • vegetables
    • soups and broths
  • Avoid fried foods and those high in sodium, protein, and sugar: These foods can promote dehydration.

There are many other causes of dehydration besides consuming alcohol. They include:

A person who is already at risk of dehydration from one or more of the above factors should avoid or limit alcohol consumption.

Consuming alcohol carries other health risks besides dehydration. These risks change depending on how much alcohol a person consumes and how often.

Moderate consumption

According to the CDC, drinking alcohol in moderation is safe for most people. A moderate amount equates to one glass of alcohol or less per day for females and two glasses of alcohol or less per day for males.

However, even moderate alcohol consumption may cause symptoms such as:

Binge drinking

Binge drinking is when a person consumes an excessive amount of alcohol within a short period of time. This equates to drinking five or more drinks within 2 hours for males and four or more drinks within 2 hours for females.

Binge drinking increases the risk of the following:

Heavy drinking

Heavy drinking can cause serious health issues. According to the CDC, heavy drinking equates to more than three drinks per day or eight drinks per week for females and more than four drinks per day or 15 drinks per week for males.

Chronic heavy drinking can result in high blood pressure, which is a leading cause of kidney disease. It can also weaken immunity, increasing a person’s risk of infections.

Chronic heavy drinking may also cause the following:

Consuming alcohol leads to dehydration and can affect several systems and functions in the body. It is important for a person to be aware of the signs and symptoms of alcohol-induced dehydration and the ways to avoid it.

Alcohol-induced dehydration is more likely to occur if an individual drinks alcohol on an empty stomach or does not drink enough non-alcoholic fluids while consuming alcohol. People who are already at risk of dehydration should avoid or limit their alcohol consumption.

Besides dehydration, alcohol can have other negative effects on the body. For this reason, a person should drink alcohol in moderation and avoid binge-drinking or chronic heavy drinking.