What causes hangovers? (And what to do about them)
Written by Luis Villaseñor (opens in a new tab)
Medically reviewed by Ecler Ercole Jaqua, MD, MBA, DABOM (opens in a new tab)
<p>Looking back, I’ve had mornings that make The Hangover look like a children’s film. Okay, not that bad, but it felt awful. My head throbbed, my body ached, and my energy was down the drain. Bradley Cooper was just acting. Real hangovers are much worse.</p><p>Now, I avoid putting myself in that position and I take the necessary steps to replenish lost nutrients and minerals. After all, the best way to fix a hangover is to avoid getting one in the first place. That might mean cutting yourself off, and not opening that second bottle of wine. But I’m no monk, and I know moderation doesn’t always happen.</p><p>So when people ask me about hangover remedies, I don’t judge, but I gently remind them that large doses of alcohol are bad for you. The damage to the gut and liver can’t easily be undone. It accrues over time, culminating in conditions like alcoholic liver disease that you don’t want.</p><p>This isn’t a revelation. Light drinking is probably okay for most people, but heavy drinking will demolish anyone’s internal organs. You want to minimize it.</p><p>Still, I recognize we’re social animals. If you do over-imbibe once in a while, all is not lost. There are still things you can do to mitigate the hangover and replenish key nutrients and minerals. But the question is: how? And what causes the hangover in the first place?</p><p>You’re about to get your answers. First, I want to talk about the liver.</p><h2>How We Metabolize Alcohol</h2><p>When you ingest alcohol, your liver freaks out. It views any amount of alcohol (also called ethanol) as a toxin. This toxin must be processed and cleared as soon as it can be done.</p><p>The liver is your largest internal organ, just as crucial for survival as your brain and heart. It regulates blood sugar levels, manages cholesterol, helps digest food, and aids in blood clotting. But the liver is best known for detoxification.</p><p>The liver first detoxifies ethanol with three sets of enzymes: alcohol dehydrogenase (ADH), the microsomal ethanol oxidizing system, and catalase. ADH does about <a href="https://www.ovid.com/product-details.12532.html" rel="noopener noreferrer" target="_blank">80% of the work</a>.</p><p>The term “detoxifies” is a little misleading, though. In fact, ADH turns ethanol into another toxin, acetaldehyde, that’s more toxic than ethanol itself. Fortunately, the liver has enzymes like aldehyde dehydrogenase (ALDH) to clean up the mess.</p><p>ALDH converts acetaldehyde (dangerous) into acetate (harmless). Finally, acetate is converted to water and carbon for easy disposal through the kidneys. Toxin cleared. Liver happy.</p><p><strong>Here’s a quick review to solidify your memory:</strong></p><ul><li>Alcohol travels from the gut to the liver via the portal vein.</li><li>Alcohol dehydrogenase converts alcohol into acetaldehyde.</li><li>Aldehyde dehydrogenase converts acetaldehyde into acetate.</li><li>Acetate is converted to water and carbon.</li><li>Obviously alcohol isn’t zapped into water and carbon immediately. The process takes time. And when someone drinks loads of beer, the liver can’t keep up. Now we’re in hangover territory.</li></ul><h2>Hangover 101</h2><p>Hangover is a catch-all term for the <a href="https://science.drinklmnt.com/did-you-know/dehydration-headache" rel="noopener noreferrer" target="_blank">headaches</a>, weakness, dry mouth, <a href="https://science.drinklmnt.com/did-you-know/what-causes-muscle-cramps" rel="noopener noreferrer" target="_blank">muscle aches</a>, nausea, vomiting, stomach pain, light sensitivity, dizziness, and shakiness that may follow alcohol intoxication. The severity of the hangover depends on several factors.</p><h3>Factors Influencing Hangover Severity</h3><ul><li>The amount (and quality!) of alcohol consumed</li><li>The time period over which the alcohol was consumed</li><li>One’s capacity to metabolize alcohol and its toxic byproducts</li><li>What you combine alcohol with (it’s not the same to drink straight or wine, vs a sugar laden cocktail)</li><li><a href="https://science.drinklmnt.com/electrolytes/how-to-test-electrolyte-status" rel="noopener noreferrer" target="_blank">Hydration status</a></li></ul><p>The first two factors are straightforward. The more alcohol the liver must process, and the less time to process it, the greater the chance and the severity of the hangover symptoms. Most people know how many drinks they can tolerate without suffering the next day.</p><p>This drink limit, however, will vary from person to person. Why? Because some people are able to metabolize alcohol more efficiently than others.</p><p>For instance, studies have found that approximately 50% of Japanese people, 35% of Chinese people, and 40% of Vietnamese and Indonesian people have an inactive variant of the <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1580147/" rel="noopener noreferrer" target="_blank">aldehyde dehydrogenase</a>. With this inactive form, alcohol consumption causes uncomfortable reactions including facial flushing, increased heart rate, and dysphoric sensations.</p><p>Finally, alcohol disrupts the delicate balance of fluid and electrolytes called <a href="https://science.drinklmnt.com/did-you-know/10-benefits-of-staying-hydrated" rel="noopener noreferrer" target="_blank">hydration</a>. The good news is, hydration is within your control. More on that soon.</p><h2>What Causes Hangover Symptoms? The Science Explained</h2><p>Most people think that alcohol causes hangovers. That’s mostly true — but it’s not the whole story.</p><p>Yes, drinking alcohol often means headache, fatigue, and nausea the next morning. But it’s not just one villain at work. Ethanol plays a role, and so do the byproducts your body creates while trying to clear it.</p><p>In other words: This is a team effort.</p><p>Here’s what’s actually going on.</p><h3>1. Ethanol — the main character</h3><p>Even before your body starts breaking it down, ethanol starts disrupting several systems that matter for how you feel the next day.</p><ul><li>It interferes with sleep architecture, fragmenting REM and deep sleep.</li><li>It alters neurotransmitters — increasing glutamate rebound and nervous system irritability.</li><li>It can impair glucose regulation, contributing to morning-after shakiness and fatigue.</li><li>It increases oxidative stress as your body works to process it.</li></ul><p>None of that feels great at sunrise.</p><h3> 2. Acetaldehyde — a toxic byproduct of alcohol</h3><p>You remember acetaldehyde. It’s the nasty toxin jammed in the middle of alcohol metabolism.</p><p>The liver works hard to convert acetaldehyde to acetate. But when too much alcohol enters the body, acetaldehyde builds up faster than the liver can clear it — at least temporarily. And that’s when the tides of war can turn.</p><p>Because acetaldehyde is directly toxic and pro-inflammatory, researchers believe it’s a likely contributor to hangover symptoms. It can trigger an immune response, causing the body to mount an inflammatory reaction. And where there’s immune activity (or inflammation), symptoms often follow.</p><p>That said, hangovers are multifactorial. Studies haven’t consistently shown that acetaldehyde levels alone predict hangover severity. Immune activation, sleep disruption, dehydration, and metabolic effects also play important roles.</p><h3>3. The diuretic effect: Why alcohol makes you dehydrated</h3><p>Centuries ago, Shakespeare noticed that consuming alcohol increased the volume of his urine. This observation has since been <a href="https://www.sciencedirect.com/science/article/abs/pii/S0025712516312512?via%3Dihub" rel="noopener noreferrer" target="_blank">confirmed by scientists</a> and more than a few inebriated humans waiting in line for the Port-O-Potty.</p><p>Yes, alcohol consumption has a diuretic effect, meaning it increases fluid loss through urine. And when more fluids leave the body than enter it, that’s called <a href="https://science.drinklmnt.com/electrolytes/dehydration-causes-and-symptoms" rel="noopener noreferrer" target="_blank">dehydration</a>. The symptoms of dehydration — headaches, lethargy, dry mouth and dizziness — align nicely with our list of hangover symptoms.</p><p>Interestingly, the diuretic effect doesn’t last. When the drinking stops, and the withdrawal begins, antidiuretic hormone rises, and more water is retained. This, unfortunately, triggers electrolyte imbalances.</p><p><strong><em>You might also like: </em></strong><a href="https://science.drinklmnt.com/electrolytes/fluid-and-electrolyte-imbalance" rel="noopener noreferrer" target="_blank"><em>Fluid and electrolyte balance: A science-backed guide</em></a></p>
<h3>4. The sodium problem: Hyponatremia and hangovers</h3><p>Electrolytes are charged minerals that conduct nerve impulses and balance your body water. How you feel is tied to your electrolyte levels, and alcohol throws these levels off.</p><p>In other words, <a href="https://science.drinklmnt.com/electrolytes/prevent-electrolyte-imbalance" rel="noopener noreferrer" target="_blank">electrolyte deficiencies</a> — provoked by drinking alcohol — can cause hangover symptoms. Here are the main deficiencies to watch:</p><ul><li><strong>Magnesium.</strong> Chronic heavy alcohol use can cause <a href="https://www.sciencedirect.com/sdfe/pdf/download/eid/1-s2.0-S0025712516312512/first-page-pdf" rel="noopener noreferrer" target="_blank">magnesium wasting</a>. This is a big problem for alcoholics, who tend to suffer clinical <a href="https://science.drinklmnt.com/electrolytes/magnesium-deficiency-symptoms" rel="noopener noreferrer" target="_blank">magnesium deficiency</a>. During isolated episodes of acute drinking, the effect is milder but may contribute to overall symptoms in sensitive individuals.</li><li><strong>Potassium and phosphorus.</strong> <a href="https://science.drinklmnt.com/electrolytes/potassium-deficiency" rel="noopener noreferrer" target="_blank">Potassium</a> and phosphorus deficiencies can <a href="https://www.sciencedirect.com/sdfe/pdf/download/eid/1-s2.0-S0025712516312512/first-page-pdf" rel="noopener noreferrer" target="_blank">develop</a> when vomiting or diarrhea are combined with electrolyte-poor diets.</li><li><strong>Sodium.</strong> In the aftermath of heavy drinking, the body activates <a href="https://www.sciencedirect.com/science/article/abs/pii/S0025712516312512?via%3Dihub" rel="noopener noreferrer" target="_blank">water retention mode</a>. This <a href="https://science.drinklmnt.com/electrolytes/sodium-deficiency" rel="noopener noreferrer" target="_blank">dilutes blood sodium levels</a>, leading to fatigue, weakness, muscle cramps, and headaches. The clinical term for low serum sodium is <a href="https://science.drinklmnt.com/electrolytes/hyponatremia-signs-and-symptoms" rel="noopener noreferrer" target="_blank">hyponatremia</a>. It makes a hangover way worse.</li></ul><h3>5: Alcohol, leaky gut, and inflammation</h3><p>Alcohol — especially in moderate to high amounts — can <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5513683/" rel="noopener noreferrer" target="_blank">increase intestinal permeability</a>, springing leaks in the delicate barrier separating your intestines from your body and triggering inflammation. This is called leaky gut.</p><p>When the gut becomes leaky, particles slip into the bloodstream, and a confused immune system attacks. Now you have inflammation, which in turn creates digestive symptoms that exacerbate hangover symptoms.</p><h2>Hangover Remedies</h2><p>Beyond moderation (or abstention), there are two main ways to mitigate hangover symptoms.</p><h3>Take Supplements</h3><p>A variety of herbs may alleviate hangover symptoms. Prickly pear extract, for instance, has been shown in a <a href="https://pubmed.ncbi.nlm.nih.gov/15226168/" rel="noopener noreferrer" target="_blank">clinical trial</a> to reduce nausea and dry mouth. Ginger can also <a href="https://pmc.ncbi.nlm.nih.gov/articles/PMC6341159/" rel="noopener noreferrer" target="_blank">soothe an upset stomach</a>. </p><p>On the hangover prevention side, a compound called dihydromyricetin (DHM) has been <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/acer.14326" rel="noopener noreferrer" target="_blank">shown</a> (in mice) to reduce intoxication behaviors and withdrawal symptoms, but its effect on acetaldehyde clearance is unclear and not well demonstrated in humans. Many companies market DHM as a hangover cure, but this is likely a misleading claim. </p><h3>Hydrate Properly</h3><p>Heavy drinking raises the risk of dehydration and electrolyte deficiency. With a hydration strategy (<a href="https://science.drinklmnt.com/electrolytes/how-to-rehydrate-fast" rel="noopener noreferrer" target="_blank">learn how to rehydrate fast</a>), some of this is preventable.</p><p>Take sodium, potassium, and magnesium along with your water. Try sipping on <a href="https://science.drinklmnt.com/electrolytes/best-homemade-electrolyte-drink-for-dehydration" rel="noopener noreferrer" target="_blank">electrolyte water</a> before, during, and after the party. Pre-load a few water bottles and you’ll be better prepared than most. I usually suggest drinking a glass of mineral-rich sparkling water for every drink of alcohol.</p><p>Yet, no amount of hydration planning will immunize you against hangovers. If you drink too much, your body will suffer. The best way to prevent a hangover is to be smart with alcohol. Less is more, as they say.</p><h2>FAQ</h2><h3>How long does a hangover last?</h3><p>Most hangovers last between <a href="https://pmc.ncbi.nlm.nih.gov/articles/PMC3827719/" rel="noopener noreferrer" target="_blank">8 to 24 hours,</a> though heavy drinking can cause symptoms that persist up to 48-72 hours. The duration depends on several factors: how much you drank, how quickly you drank it, your ability to metabolize alcohol (thanks, liver enzymes), and your hydration status.</p><h3>Can you prevent a hangover completely?</h3><p>Avoiding alcohol consumption is the only 100% guaranteed prevention method. If you choose to drink, moderation is your best bet. A few things may help you reduce hangover severity (though not eliminate it). These include drinking water and electrolytes before, during, and after alcohol consumption, eating a substantial meal before drinking to slow alcohol absorption, and pacing yourself — giving your liver time to process the alcohol.</p><h3>Do electrolytes help with hangovers?</h3><p>Electrolytes don't "cure" hangovers. They can't speed up your liver's processing of acetaldehyde, which is the primary culprit behind your misery. But they do help with several hangover symptoms, particularly those related to dehydration and electrolyte imbalances.</p><h3>Are hangover pills and supplements effective?</h3><p>Mostly no. There’s limited evidence for a few things that might help a little: </p><ul><li><strong>Prickly pear extract:</strong> One <a href="https://pubmed.ncbi.nlm.nih.gov/15226168/" rel="noopener noreferrer" target="_blank">clinical trial</a> showed it reduced nausea and dry mouth. Not a cure, but potentially helpful for symptom relief.</li><li><strong>Ginger:</strong> Can <a href="https://pmc.ncbi.nlm.nih.gov/articles/PMC6341159/" rel="noopener noreferrer" target="_blank">soothe an upset stomach</a>, which is useful when you're nauseous. But it won't address the underlying acetaldehyde problem.<strong></strong></li><li><strong>Dihydromyricetin (DHM): </strong>Showed promise in <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/acer.14326" rel="noopener noreferrer" target="_blank">mouse studies</a> for speeding acetaldehyde clearance. Many companies market DHM as a hangover cure, but human evidence is lacking. Be suspicious of these claims.</li></ul><p>But there is no evidence to suggest that “hangover cure supplements”, activated charcoal, milk thistle (traditionally used for liver support, but no hangover evidence), or B Vitamins will <em>cure </em>a hangover. Focus on moderation, <a href="https://science.drinklmnt.com/electrolytes/how-to-rehydrate-fast" rel="noopener noreferrer" target="_blank">hydration with electrolytes</a>, and giving your body time to process the alcohol and clear the acetaldehyde.</p><h3>Does “hair of the dog” work?</h3><p>No. The idea behind "hair of the dog" — drinking more alcohol to cure a hangover — comes from <a href="https://www.sciencedaily.com/releases/2017/02/170214163637.htm" rel="noopener noreferrer" target="_blank">16th-century medicine</a>. Doctors back then thought you could cure rabies by drinking a potion made with hair from the dog that bit you. (Spoiler: that didn't work either.)</p><p>When you drink more alcohol in the morning, you might feel temporarily better because you're getting buzzed again. You're essentially delaying the inevitable by putting more ethanol in your system, which briefly masks the withdrawal and acetaldehyde effects. But you haven't fixed anything. You've just postponed the hangover. When it finally hits, it'll be worse because now your liver has even more alcohol to process. You're adding fuel to a fire and calling it firefighting.</p><p>Time is the only universal cure for hangover symptoms. There's no shortcut.</p><h2>The Bottom Line</h2><p>Hangovers are caused primarily by acetaldehyde (a toxic byproduct of alcohol metabolism), dehydration from alcohol's diuretic effect, electrolyte imbalances, and inflammation. You can reduce severity by staying hydrated with electrolytes before, during, and after drinking — and most importantly, by drinking alcohol in moderation.</p>