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How Does Drinking Cause Dehydration?

Berocca Hangover Cure

Pretty much everyone remembers from their junior high and middle school health classes that drinking causes dehydration. Most people also realize that dehydration is also partially responsible for morning hangovers. What many people don’t realize, however, is how it works. In this Hangover Chronicle, we will endeavor to explain what dehydration is, how alcohol can play a part in dehydration, why the myths for hangover cures don’t work, and what you can actually do to get rid of a hangover, especially if you are partying with us on vacation in Key West.

What is Dehydration

The concept behind dehydration is simple. Dehydration is simply a lack of water in your body. Every organ function, from the skin to the brain and heart, needs water to function, carry fluids, allow blood to travel freely, to get rid of waste. A lack of water means that the body can no longer continue performing its function with ease. If dehydration is bad enough, some organ systems can sometimes stop functioning altogether, sometimes for good. The more water you drink and your body is able to retain, the better.

How Alcohol Causes Dehydration

How Does Drinking Cause Dehydration? | Hangover Hospital Key WestEthanol, the main ingredient in the drinks we call “alcohol” is a natural dehydrator. When you drink, alcohol hits the stomach and almost immediately gets absorbed by your stomach tissues. Any ethanol/alcohol left from the stomach, such as that which was absorbed by your food, then travels to the small colon where the rest of it is absorbed. The alcohol then travels through your blood and throughout your whole body, including your brain, but it all filters down to your liver and kidneys which have the job of cleaning up your blood and the alcohol that runs through it.


The kidneys specifically have the job of regulating your urine. They only know how to do this because of a hormone the brain produces called anti-diuretic hormone. A diuretic is something that causes you to pee (ethanol is a diuretic, for example), so this anti-diuretic hormone tells the kidneys to keep water in, or at least regulates how much water should be released that is still healthy for the body.

The problem is that, because of some complex and very technical processes, alcohol tells the brain to quit making anti-diuretic hormone. With no regulator in place, your kidneys allow any water to pass right out of the body. This is the first and most common reason for dehydration, and it explains why you can’t stop using the bathroom when you are partying with your friends. You lose a lot of water that your body needs but is no longer able to keep in when you are drinking, and the problem only gets worse with more and more alcohol.

Another way dehydration can occur is because of vomiting. Vomiting makes you lose necessary hydration (which you can get from both food and non-alcoholic drink) because of signals the stomach sends the brain that you have consumed toxins. The brain then instructs the stomach to vomit, as the stomach is the first line of defense for toxin excretion in the body. By the time your brain receives these signals, however, it often too late and the alcohol is already absorbed. When you vomit after drinking, you only end up losing nutrition.

  • The last way that alcohol affects your body’s hydration levels is through diarrhea. Alcohol prevents the body from absorbing water in the colon, which makes your stool and water pass together.
  • When you get the runs after drinking, it is likely fluid and food that your body wasn’t able to process. With diarrhea, vomiting, and a lot of urine, you have a perfect storm for dehydration, one of the main factors for a hangover.

How Dehydration Plays a Part in a Hangover

How Does Drinking Cause Dehydration? | Hangover Hospital Key WestDehydration causes bad hangovers for a few reasons. First, you lose electrolytes. Electrolytes are legitimate “rocks”, or “minerals” as we know them in our food, that help our bodies function. Electrolytes control the amount of water our cells receive and as well as how other nutrients are absorbed for energy so organs can do their jobs correctly. When dehydrated, these electrolytes are also lacking, wherein the cells begin to either ache or die, causing pain. This is why people often feel achy after a night of drinking.

When there is not enough water or nutrients to aid in your body’s normal processes, different organ systems send distress signals to the brain. These stress signals are interpreted as a headache, but they essentially let you know that something is wrong with other parts of your body. Splitting migraines in a hangover are ultimately the result of several parts of your body telling you it feels like crap.

  • In addition, many scientists blame low blood sugar levels caused by dehydration (sugars which are needed to give your cells energy to do their work) as engendering a hangover, along with congeners, which you can read about here.

Why the Myths Don’t Work

How Does Drinking Cause Dehydration? | Hangover Hospital Key WestKnowing what you now know about dehydration and the role alcohol plays in it, you can now start to understand why some of the common misconceptions about hangover cures don’t work. You can’t drink more water to offset dehydration because it can’t be absorbed. Greasy foods further dehydrate your body (albeit they do provide some electrolytes). Drinking more as a “hair of the dog” solution is just stupid because it leads to further kidney and liver damage and dehydrates you further. And a cup of coffee, which has caffeine, also a diuretic, won’t help you keep in your fluids.

What Does Work

How Does Drinking Cause Dehydration? | Hangover Hospital Key WestNo doubt, some hydration is better than nothing, so if you feel sick in the morning, eating a nutrient-rich breakfast and getting fluids back into your body will make a big difference. You may also consider some light stretching and exercising to invigorate your muscles and organs, but there is no guarantee that doing any of this will get rid of your hangover, which really sucks if you, let’s say, are on vacation in Key West. Fortunately, there is a faster, more guaranteed way of getting rid of your hangover symptoms. Call us at Hangover Hospital. We come directly to you and provide you with IV hydration and electrolyte therapies that have a 100% absorption rate, meaning in less than an hour, you will be back on your feet.