The Science of a Hangover

I have a love hate relationship with wine – I love it and it hates me. That’s at least the way it seems the morning after we’ve been in close proximity. But why does alcohol make you feel so rotten the morning after and can the dreaded hangover be avoided? I decided to look into the science behind a hangover and see whether I can enjoy a glass of pinot without wanting to spend the next day in bed eating my own body weight in carbs.

Cause number 1: Dehydration

Most people are aware of the fact alcohol is diuretic, which means it makes you wee more. The result is that the next morning you run the risk of dehydration along with a dry mouth and headache. Lovely stuff.

Prevention: Try to drink water between alcoholic drinks and/or drink water before you go to bed.

If you’ve ever tried the approach of downing a pint of water before you go to bed after a heavy night on le booze you’ll be aware of the fact that, although it may help, it doesn’t mean you get away hangover free. So there must be more to a hangover than just the dehydration… In fact, it turns out alcohol is pretty poisonous and not just in the “what’s your poison?” sense, more in a surprisingly toxic way.

Cause number 2: Acetaldehyde

When we drink alcohol it is absorbed into our blood stream and works its way around our body. When it reaches the brain it makes you feel relaxed an uninhibited, which is the part we all enjoy, however this is not the only place alcohol leaves its mark. In the liver alcohol is metabolised (broken down) into different compounds which can then be removed from the body as waste. This process requires several steps before the final non-toxic products of water and carbon dioxide are made.

The first step is to turn the alcohol into acetaldehyde using an enzyme called alcohol dehydrogenase. The side effects of having acetaldehyde in your system include nausea, headaches and vomiting – sound familiar?

: There is none. I know – rubbish. You just have to wait for your body to metabolise the acetaldehyde into its less harmful by-products. So unfortunately if you spend the morning having an unwanted date hugging the toilet you just have to wait it out. As acetaldehyde is even more toxic than alcohol moderation is probably the key.

Cause number 3: NAD+ depletion

The metabolism of alcohol and acetaldehyde use a compound called NAD+. This NAD+ is also vital for the day to day health of your cells. It helps converts water, oxygen and a compound called pyruvate into energy. If the NAD+ has been used up metabolising alcohol, your cells need to make more. The cells convert pyruvate into lactate and this reaction produces more NAD+. Unfortunately  long term build up of lactate is also linked to kidney damage. The more I read about alcohol the more I realise it’s pretty nasty stuff! The second consequence is that when pyruvate is converted to lactate, your liver becomes less efficient at regulating your blood sugar levels and blood sugar can become very low. Ever had the desire to eat the entire contents of your cupboards post pinot? That’ll be the low blood sugar.

Prevention; There’s not a lot you can do about the depleted NAD+ other than wait for your liver to do its magic (otherwise known as metabolism) and restore the natural balance. As for the low blood sugar, based on the assumption you’re not still hugging the potty, it’s a good idea to make sure you eat. That’s a free pass for a one way ticket to pasta-ville in my eyes.

Cause number 4: Reactive oxygen species and cell damage: 

I’ve grouped these together because I don’t think it’s fair to say they cause a hangover  however for regular drinkers they probably represent the biggest danger since they can cause longer lasting damage.

The acetaldehyde that is made during alcohol metabolism is a bit of a renegade and can attach itself to things in the cell that it shouldn’t, including a protein called glutathione. When attached to acetaldehyde, glutathione is prevented from doing other important jobs inside the cell which, when experienced regularly can lead to cell damage . More worryingly acetaldehyde can also bind to DNA and damage it, which can increase the risk of developing cancer.

There is a separate chemical pathway that your liver cells can use to metabolise alcohol. Instead of using alcohol dehydrogenase it uses an enzyme called cytochrome p450. This method of alcohol breakdown still produces acetaldehyde but has the added bonus of churning out reactive oxygen species. These little nasties are, as the name suggests, incredibly reactive. They can cause a lot of damage to your cells by reacting with proteins and DNA. This method of breaking down alcohol is used far less by your cells than the alcohol dehydrogenase method so the less you drink the less likely you are to produce the reactive oxygen species.

Prevention: Eat food rich in cysteine post alcohol which includes eggs, chicken and oats. Cysteine is an important building block of glutathione, so making sure you get more into your body gives your cells a fighting chance at making more glutathione. Have a glass of vitamin C rich orange juice. Vitamin C is powerful anti-oxidant, meaning it can interact with the reactive oxygen species, preventing them from reacting with protein and DNA in your cells.

I’m sorry to say the best prevention for a hangover and damaging your health long term is avoiding alcohol in the first place. Regular exposure to alcohol and the damage caused to cells is linked to an increased chance of developing cancer. To me this is a far more important reason to avoid drinking than a fuzzy head the morning after and is a very good argument in favour of moderation.  If you feel drunk that means there’s too much alcohol in your body for your liver to metabolise and you’re getting a backlog of alcohol related nasties in your system – so moderation really is key. On that note, if someone can recommend a low alcohol wine that doesn’t taste like a mix of sugar water and ass, please do let me know.

Post by: Liz Granger

Twitter: @Bio_Fluff


Bullock, C. (1990), The biochemistry of alcohol metabolism — A brief review. Biochemical Education, 18: 62–66. doi: 10.1016/0307-4412(90)90174-M.

Wu, D. and Cederbaum, A. I. (2003) Alcohol, Oxidative Stress, and Free Radical Damage.

HK Seitz, P Becker  (2007) -Alcohol Metabolism and Cancer Risk. Alcohol Research and Health Vol. 30, No.1: 38-47.

20 thoughts on “The Science of a Hangover”

    • The alcohol in vodka causes the same side effects as the alcohol in any other drink, but the vodka may be ‘purer’ and contain fewer chemicals. Some processed drinks (usually bright blue) have colourings, preservatives and other chemicals that could potentially have unwanted negative side effects making a hangover worse. Also, darker liquors like whisky have compounds called congeners that contribute to their distinctive taste but can make a hangover worse.

      I can, however, vouch for the fact if you drink enough vodka you still get a good old fashioned alcohol induced hang over.

  1. If you are talking about red wine only, don’t forget the sulphite that is added as preservative in American wine and wines imported to America. There are numerous personal anecdotes from travelers about the general lack of hangover from drinking sulphite-free wine.

    You have also neglected to mention that alcohol causes the kidneys to excrete magnesium, a vital mineral that regulates energy metabolism (NAD), water balance, and brain function (headache).

  2. I heard that alcohol consomption leads to increased alcoholdehydrogenase production. Does that feedback mechanism exists and is it true that this way you can get “training” in drinking? The hangover would be reduced if the concentration of ADH in the liver is higher, right?

    • It seems likely that more ADH would be produced in response to repeated exposure to alcohol. I read a paper about alcohol clearance that I think confirmed this (people who were given a large amount of alcohol every day for 3 weeks processed the alcohol much faster) but the paper is on a different computer that I can’t access right now.

      Based on the assumption an individual does have more ADH, theoretically it could help reduce a hangover but in practice I’m not sure it would. If they have more ADH they are likely to drink more alcohol without feeling drunk – people who drink a lot do tend to build up a tolerance. This is because alcohol is being removed from the blood stream by the liver a lot more quickly. This could lead to an increase of acetylaldehyde in their system and also a greater chance of becoming dehydrated due to the fact they’ve consumed more alcohol. So the hangover could actually be a lot worse.

      Hope this answers the question. I’ll pop up some links to papers when I have access to my work computer.

      • An interesting revelation linked to this point is the difference between the levels of ADH in the stomach of men and women. Women are consistently seen to be more susceptible than men to alcohol and of course part of this can be put down to body weight etc. but women are generally found to have a lower concentration of ADH in their stomachs. This does vary with age but could in part explain the increased susceptibility. Interesting to see that there are variations in this ‘first-pass metabolism’ of alcohol but how this relates to the extent of hangovers I do not know.

        Good article Liz.

        • Thanks Olly! 🙂 I *think* I read somewhere men have more ADH on the lining of their oesophagus too, which also helps with ‘first pass metabolism’. I might have to stick to half pints in future….

        • what about those of us who don’t get hangovers? I’m a 26 year old woman of average size. I’ve never had a hangover in my life even after drinking a lot and my friends get hangovers after drinking the same amount. I also hold my liquor very well, most people can’t even tell i’m that drunk most of the time, my mom being the exception lol. I swear, sometime I feel like i’ve missed some right of passage by never having a hangover haha.

      • Mixing different types of alcoohl makes a hangover worse, this is just a myth. On the other hand, liqueurs people act differently, so if you do not know what works for you, and you like to drink different things you can get into trouble. Scotch puts me to waste a drink. I know one person who can not take place the vodka at all, and another man who will have the worst hangover when he touched a drop of tequila. A hangover is actually mild dehydration. Alcohol makes you pee a lot, and the water leaves the body. The best way to prevent a hangover is to drink water. I try a glass of water for every drink I have after the second or third. I’ve never had a hangover worse than a mild headache and a feeling woozy.

  3. The best is not to drink at all, that is an obvious advice. The health benefits of drinking alcohol, especially red wine, are attributed to the “Resveratrol” which become available in different forms (tablets, liquid, and powder) over the counter in any health shop. No more excuse.

    • Stop drinking, love hhaahhaha.Again .. seriously.You can be as bad as I do, and no, I have no hangover the day but this morning.I .. hmmmmmmm.How is early too early? ?

  4. Does eating lots of salad and Roasted Chicken N Curry Helps Kidney
    To Fight alcohol
    I drink twice a month
    eat lots of salad ,Roasted chicken and curry
    and drink at least 2 liter of water before and while nap.
    It helps me avoid Hangover
    It cut down my hangover to 70%

  5. It doesnt matter if your wine has no sulphites or if you are drinking vodka, you WILL get a hangover because there is still alcohol in these drinks….

  6. People will often comment that they just cant drink like they did when they were younger. I have noticed this to be true personally in that it takes less to get a hangover. Does this change in tolerance have anything to do with a build up of toxins in the body as we get older?

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