The science behind hangovers — and what to do when you get one 

Dec 23, 2020 /

Most of us love to joke about hangovers.

For example:
What’s the best thing for a hangover?
Drinking heavily the night before.

But what is happening in our bodies is more serious than that — it’s alcohol withdrawal. Yes, the symptoms are less extensive, unpleasant and life-threatening than those an alcoholic will go through. But however you dress it up, your brain and body are withdrawing from alcohol.

Hangovers are the experience of various unpleasant physiological and psychological effects that follow a medium-to-high consumption of alcohol. Typically, it comes on around 10 hours after your blood alcohol peaks — but this varies according to sex, weight and genetic disposition.

However, some people don’t get hangovers at all: Between 3 percent and 23 percent of the population is reported to be hangover-resistant. Not surprisingly, these people may be more likely to become heavy drinkers, as they don’t experience the deterrent effect of hangovers.

Hangovers can last from a few hours to over a day. As alcohol affects so many systems in our bodies and brains, a hangover is equally complex so there are myriad possible ways to suffer.

Hangovers: What’s happening in our bodies and brains? 

There are gaps in the research about what is going on in our bodies during a hangover. But researchers know the hangover state is a multifactorial event caused by a variety of biochemical and neurochemical changes, as well as your personal make-up.

You’ve poisoned yourself

One of the ways that alcohol is metabolized in our bodies is by the enzyme alcohol dehydrogenase (ADH). As ADH breaks down ethanol, it forms acetaldehyde, which is a poison and a carcinogen. This is relatively quickly turned into acetate, then finally into carbon dioxide and water.

Some people have genetic variants of the enzymes that make this breakdown faster or slower. What’s known from studying those slow to break down acetaldehyde is how unpleasant it makes people feel — flushed, nauseated, rapid heartbeat — and hangover symptoms may come from the acetaldehyde hanging around in their bodies.

Consuming high quantities of congeners — chemical byproducts produced during fermentation and distillation processes — is also thought to make hangovers worse. There are high concentrations of congeners in red wine and distilled spirits, for example, and low ones in clear spirits such as vodka.

Congeners include acetaldehyde, acetones, histamines and methanol. Methanol, a product of sugar fermentation, is thought to be a major contributor to the symptoms of hangover. ADH metabolizes methanol at a slower rate than ethanol to form formaldehyde and formic acid  — which are both highly toxic.

Your neurotransmitters have gone haywire

Two important neurotransmitters are glutamate and GABA. Glutamate turns on the brain, while GABA turns it off. Our brains have evolved so every time glutamate is released, GABA is released too. It’s a beautifully balanced system.

When you drink alcohol, it stimulates GABA. Initially, this makes you feel relaxed but as you consume more alcohol, it can switch off important parts of the brain, such as those affecting  judgment and consciousness. At the same time, alcohol blocks your glutamate receptors, and as your alcohol level rises, you start to lose the capacity to lay down memories.

When we drink, the imbalance between GABA and glutamate — that is, too much GABA and too little glutamate — has been shown in rodents to correlate with the intensity of withdrawal.

You are inflamed 

The inflammatory response happens when your body is damaged, and although it’s part of the immune system’s natural response, it can be destructive. Chronic inflammation is believed to be a significant factor in many long-term health conditions, from diabetes to cancer and liver cirrhosis.

By harming the blood vessels and your gut, alcohol causes the body to turn on itself. The inflammatory response is unpleasant — symptoms include nausea, vomiting, headache, confusion and tremor, as well as clinical depression, which induces mood changes, cognitive impairment and learning and memory deficits.

You’ve caused mitochondrial dysfunction 

Alcohol also damages mitochondrial DNA, particularly in the liver. Mitochondria, the energy-producing machines in our cells, are susceptible to damage from the free radicals produced by alcohol via acetaldehyde. Even slight damage to the mitochondria can lead to toxicity in brain regions.

Where do hangover symptoms come from?

Can’t bear light and sound 

This is linked to glutamate rebound. Alcohol suppresses glutamate activity in the brain, and after you stop drinking, your body tries to compensate for this by increasing glutamate production.


This may also be linked to glutamate rebound, plus acetaldehyde dilates the blood vessels in our heads. New research also suggests alcohol may cause your immune system to attack your body and release chemicals that cause irritation in blood vessels and nerves, leading to pain including headaches. Headaches may also be tied to dehydration caused by the diuretic effects of alcohol.

Stomach symptoms 

Alcohol damages the stomach and intestine lining, so it can give you diarrhea and leave you feeling nauseated. It may cause a tiny bit of inflammation in your pancreas too.

How you can prevent a hangover 

Drink less 

You know this already.

Pace yourself 

It takes about an hour-and-a-half for our bodies to process a standard drink. If you drink slowly, your body will have a greater chance to process alcohol — which means your blood alcohol peak won’t be as high — and it’s been shown to give less of a hangover.

Drink water with your alcoholic drinks 

Other ways to dilute alcohol are to add more ice to drinks; soda to wine or lemonade to beer; or more non-alcoholic mixers to spirits. Flat liquids are better since fizzy drinks could make you absorb alcohol faster.

Drink smaller measures 

Shrinking glass size has shown to result in consuming less booze over the course of an evening.

Drink clear spirits 

These contain fewer congeners. One study showed that vodka produced a lesser hangover than whisky — although sleep and next-day concentration were bad in both vodka and whisky drinkers.

Hangover cures: What’s the evidence? 

You can’t “cure” a hangover, but you can treat your symptoms.


Take ibuprofen when you go to bed and/or when you wake up. Ideally, take them with food since  they can be harsh on the stomach lining.

Beta blockers 

Note: These must be prescribed and are not approved to treat hangovers! They can slow down the pounding feeling in your head by reducing your heart rate, but I’m not sure if they do more than that.

Hair of the dog, or any so-called cure that contains alcohol 

This is the very worst thing you can do. By putting alcohol back into your body and brain, you are only delaying your hangover!


Although there’s no research backing up hydration, it theoretically makes sense. But I would not recommend getting hooked up to IV hydration unless you’re in a hospital.


If you have a hangover, you’ll likely wake up with low blood sugar, which is why eating carbs can make you feel better. Eggs, in particular, contain a lot of the nutrients your body need.


Any caffeine will help you feel more awake.


Probiotics are known to reduce leaky gut, and a very small study of heavy drinkers showed the subjects who took probiotics had reduced levels of inflammation in their bodies.

Herbs and supplements 

Most of these have no evidence, although it might be worth your taking a B vitamin complex.  Some companies are developing combination treatments to speed up alcohol metabolism — they seem promising but expensive.


In theory, any exercise you do will speed up your metabolism and shift your hangover. However, you are unlikely to feel like doing this.

Here’s why you should be happy if you get a hangover

Sensible drinking is about restraint, which might be easier when you know that alcohol impairs you the next day.

Excerpted from the new book Drink?: The New Science of Alcohol and Your Health by David Nutt. Reprinted with permission from Hachette Go, a division of Hachette Book Group, Inc. Copyright © 2020 by David Nutt.

Watch the TEDxBrussels Talk from Dr. David Nutt here: