The Science Behind a Hangover
By Devin Bohbrink
Updated on December 28, 2022

The Science Behind a Hangover

If you’re here, you’re probably dealing with a hangover. We’ve all been there. You went out after work with your coworkers and had one too many at Happy Hour. Now, you’re glued to the toilet and aren’t sure you can make your next Zoom meeting.

You’re definitely not alone here. Anyone who has consumed alcohol has experienced hangover symptoms at one point or another. If you drink alcohol, it’s unavoidable. While you probably feel awful on the outside, you may not know what’s going on inside your body that’s making you feel this way. 

With the holidays just around the corner, it’s time to be in the know about how a hangover works. Knowing what it is that makes a hangover happen can help you avoid worse symptoms in the future. We’re going to cover what causes a hangover, why it happens and what you can do to make your next one more bearable. 

What is a Hangover?

First, we need to understand what a hangover is. Sure, you know that it causes you to vomit and miss that Saturday morning jog, but there’s more going on behind the scenes. 

The term ‘hangover’ is defined as disagreeable physical effects following heavy consumption of alcohol. Simply put, it’s what happens when you drink too much. Typical symptoms of a hangover include: 

  • Headache
  • Fatigue
  • Nausea
  • Muscle Aches 
  • Stomach Pain
  • Digestive Issues 
  • Anxiety
  • Sweating
  • Increased Blood Pressure
  • Dizziness
  • Poor Sleep 


The list goes on and it’s important to remember that everyone is different. Your hangover symptoms won’t be exactly like someone else. You also may experience a different hangover everytime you drink, so it’s hard to be prepared! 

What Causes a Hangover?

When discussing the cause of a hangover, we have to make the distinction between how alcohol affects the body, and what’s causing the hangover. First, we’ll look at how alcohol affects you once you start drinking. 

What Happens to Your Body When You Start Drinking Alcohol?

When you drink alcohol, your body doesn’t digest it like food. Alcohol is water soluble, so it absorbs into the body instead. When it’s absorbed, it passes into your bloodstream and travels throughout the body, affecting your organs. 

The first area that alcohol affects is your bloodstream. If you get red when you’re drinking, it’s because the alcohol is widening your blood vessels. Alcohol can also cause a drop in blood pressure. 

How alcohol affects you once it’s in your bloodstream is going to depend on your:


  • Weight 
  • Age 
  • Sex 
  • Metabolism 
  • Strength of the alcohol
  • Medications 
  • How much you’ve had to eat


After alcohol is in your bloodstream, it gets to work on your organs. If you haven’t eaten much that day, alcohol will absorb into your bloodstream very quickly and you’ll feel the effects almost instantly. Most importantly it affects your brain, kidneys and liver. 

The Brain

Once you start drinking, alcohol begins to dull the parts of your brain that control your body. It affects the ability to make decisions. You’ll feel happy and uninhibited, but then you may start to slur your words and become clumsy. Long term use may cause permanent problems, as well. 


Since alcohol is a diuretic, it puts your kidneys to work. When you’re out for drinks, you’ll probably notice that you’re going to the bathroom more than normal. This is because alcohol interferes with your kidneys’ ability to absorb water, so it will go right through you. This will also cause dehydration and extreme thirst, which can lead to hangover symptoms. 


When you’re drinking alcohol, your liver breaks down about 90-98% of it. Your liver can only break down about one unit (one drink) of alcohol per hour, so when you overload it with drinks, that’s when you start to feel drunk and your liver gets to work. 

Why Does Drinking Alcohol Cause a Hangover?

Now that we know what alcohol is doing inside your body, let’s talk about what happens the next day. This is the part where you’re vomiting and can’t get out of bed. There are several factors that can cause the dreaded hangover symptoms. 


Dehydration is not a hangover symptom, but it can cause them within the body. This is because alcohol releases vasopressin, which is the hormone that tells the kidneys to hang onto fluid. Without it, water is passing right through you, hence the long bathroom lines at the bar. Dehydration can cause those horrific hangover headaches and fatigue. 


Alcohol is known to increase inflammation in the body. Inflammation can make you feel fatigued and overall bad. It can also contribute to hangover symptoms. Alcohol is also known for inflaming the stomach lining, which can cause gastrointestinal issues during a hangover. Grab some TUMs to be on the safe side. 

Poor Sleep

Not getting enough sleep can also make your hangover worse. You’re already not getting quality sleep when you’ve been out drinking, and you’ll typically wake up randomly in the night. Not to mention, you probably didn’t go to bed early. Poor sleep will make you feel more fatigued and contribute to other hangover symptoms such as headaches. 


When alcohol is metabolized, it creates a byproduct called acetaldehyde. This toxic compound can cause inflammation in the GI tract, causing hangover symptoms such as upset stomach and nausea. 

Is a Hangover Dangerous? 

While a hangover can seem like the end of the world, they aren’t dangerous. As long as you take care of yourself afterwards, the symptoms will go away and you’ll return to your normal self. All it takes is time. 

Can You Cure a Hangover? 

No, you cannot cure a hangover. Once the damage is done, you must face the consequences of your big night out. You might get lucky and only suffer a little fatigue, or you’ll get the full body experience hugging the toilet. The only thing you can do is take care of yourself and rest. You can also try to ease your symptoms by: 

  • Hydrating
  • Sleeping well 
  • Eating a nutritious meal the night before
  • Taking ibuprofen
  • Get outside for some fresh air

When you’re hungover, it’s important to take care of yourself. Keep in mind that a hangover can have lingering symptoms from last night’s antics. Don’t operate any workout equipment or do anything strenuous. 

What Can You Do to Avoid a Hangover?

Keep in mind that the only way to truly avoid a hangover is to not drink. There are steps you can take before going out that can help you have less severe symptoms the next day, such as: 

  • Setting a drink limit
  • Sticking to clear liquors
  • Eating a full meal before you go out 
  • Drinking water between alcoholic drinks 

Hangover Final Thoughts

The bottom line is that hangovers are never fun. Knowing how they work within the body can help you avoid worse symptoms the next day. It’s also good to be informed about the substances that you’re putting into your body. 

Alcohol doesn’t just give you a headache. It affects you internally, externally and lifelong if you let it. We encourage you to always have fun and please drink responsibly. 


Devin Bohbrink

I'm a content writer from Chicago that loves her cocktails. Let's talk all things hangover, and how we can get rid of those nasty symptoms after a night out.

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