Why Does Alcohol Make You Poop?

Written by Emma Loewe: Writer, author, and editor of Cultured. Her writing explores the intersection of nature, climate, and human health. Emma is the author of “Return to Nature” and “The Spirit Almanac.”
Reviewed by Jennie O’Grady: Senior SciComms Specialist at Seed Health

Happy hours can lead to decidedly unhappy trips to the bathroom. Whether you know them as hangover poops, rum bums, or day-after-drinking sh*ts (DADS), the bowel movements that follow a bout of drinking can sometimes come out more liquid and shall we say, urgent, than usual. 

For the 2 billion people who regularly consume alcohol, these fast and furious BMs reveal quite a bit about the inner workings of the gut microbiome and how it responds to booze.¹ 

Knock back this primer to find out why alcohol makes you poop, which beverages are less disruptive to the gut, and how to offset some of the stomach-rumbling side effects of boozing.

Your Bowels on Booze

Alcohol can lead to looser, more sudden stools due to its effects on the gastrointestinal (GI) tract and the gut microbiome.

Let’s cover its impact on the GI tract first: Ethanol (the active component in alcoholic bevs) is, as you probably know, a toxin. When healthy, our bodies work to metabolize it and get it out of our systems as quickly as humanly (or microbially) possible—but it still does some damage along the way. 

Most of this processing happens in the liver, where ethanol is converted into acetaldehyde—another highly toxic and carcinogenic compound. This acetaldehyde can harm the mucosal lining of the GI tract and increase gut permeability, which may allow harmful toxins to escape the gut and circulate throughout the body. Cue: inflammation and irritation.^2,3,4

Your intestines put some of the finishing touches, so to speak, on your stool before it exits the body. One way they do so is by absorbing excess water from stool and returning it to the bloodstream.⁵ When inflamed, your intestines can’t absorb this water as efficiently.⁶ And what you don’t absorb, you expel—hence why your poops may be mushy, liquidy, or otherwise outliers on the Bristol Stool Chart after boozing.

Ethanol also stimulates the release of certain chemicals that can enhance bowel contractions (like prostaglandins) and inhibits other hormones that promote the reabsorption of water in the kidneys (like vasopressin).^7,8 This is why you may notice that you have stronger urges to use the bathroom (for both no.1 and no. 2) while drinking.

These diuretic effects can lead to dehydration and electrolyte imbalances, further stimulating bowel movements. If your drink of choice is carbonated, you may also feel gassy and bloated while imbibing—stimulating the urge to go even more.

This doesn’t just happen after binge drinking (defined as four or more drinks in a single sitting for women, and five or more for men).⁹ Even moderate drinking (one drink per day for women, two drinks per day for men) may speed up the rate of digestion, potentially causing diarrhea.¹⁰ 

How Alcohol Disrupts Your Gut Microbiome

The community of bacteria that inhabit your gut is a conduit between your GI tract and brain, your liver, and your immune system. Here are a few ways that alcohol seems to impact the gut microbiome—and the rest of the body by extension: 

• The ethanol in alcohol disrupts the balance of gut microbiota by reducing beneficial bacteria like Lactobacillus and Bifidobacterium and promoting the growth of harmful bacteria such as Enterobacteriaceae. This dysbiosis (imbalance) can weaken the gut’s protective barrier, further increasing intestinal permeability and causing digestive disturbances like those covered above. Even isolated bouts of binge drinking have been shown to reduce the richness of the gut microbiome and contribute to dysbiosis in preclinical models.^1,11
• Alcohol doesn’t just impact the types of bacteria that populate the gut; it seems to affect their function, too. In the process of metabolizing (processing) material, bacteria in the gut produce short-chain fatty acids (SCFAs). These SCFAs are jacks of all trades in the health department, helping to support the intestinal barrier, reduce inflammation, and more.¹² People with alcohol use disorder tend to have fewer SCFAs in their guts than non-drinkers, suggesting that alcohol impedes the production of essential microbial metabolites.^13,14
• The liver is one busy organ. Not only is it responsible for processing toxins (like alcohol), but it also plays a key role in gut health thanks to the gut-liver axis.¹⁵ As the liver produces bile (a fluid that’s essential for effective nutrient absorption), it sends compounds called bile acids to the intestines to help digest food. In the gut microbiome, these “primary” bile acids are converted into secondary bile acids before being recycled and sent back to the liver for reuse.¹⁶ Excessive alcohol intake throws off this mutually beneficial relationship in a few ways. It can impair bile production, leading to fat malabsorption and resulting in diarrhea or steatorrhea (fatty stools).¹⁴ From there, lower levels of bile acids in the gut could lead to inflammation, damage of the intestinal lining, and an overgrowth of bacteria and potential pathogens (for example, Clostridium difficile).^17,18,19 Alcohol-induced dysbiosis in the gut can also lead to more bile acids being recycled back to the liver, kicking off a negative feedback loop that can contribute to severe liver damage over time.¹⁷

EXPLORE FURTHER: How Alcohol Damages Your Microbiome

The Hardest (and Easiest) Alcohols on Your Gut 

While alcohol is never “good” for gut health, some types seem to be less harmful than others (when consumed in reasonable amounts). 

Red wine, for example, is rich in polyphenols, which have been observed in studies to increase the diversity of the gut microbiome.²⁰ When you sip a glass of red or white, you may also combat certain pathogens in the oral microbiome due to wine’s unique mixture of antibacterial organic acids.²¹ 

Due to the way they’re made, fermented drinks (like cider and mead) may also contain gut-healthy components such as polyphenols, amino acids, vitamins, and probiotic microbes.

And good news for lager lovers: There is some evidence that ingredients in beer (such as polyphenols, fibers, and melanoidins) may have an antioxidant and anti-inflammatory effect on the gut microbiome. Researchers even predict that “functional beers” fortified with additional fibers, antioxidants, and probiotics could be in our future—but they’ll likely be alcohol-free or low in alcohol.²² 

Drinks with a higher ABV (alcohol by volume) tend to be absorbed more quickly, and they may be more disruptive to digestion—especially when consumed in excess. Research shows that beverages around 20–30% ABV (such as liqueurs and fortified wines) can be absorbed in the gut more quickly, potentially causing diarrhea, while those with a 40% ABV (most spirits) may have the opposite effect.²³ 

This is why you may feel the urge to poop after 1–2 beers or glasses of wine, but you may feel more constipated after a night of heavy drinking with hard alcohol. 

How to Protect Your Gut When You Drink

Want to avoid uncomfortable post-alcohol poops? Looking to protect your body from the worst impacts of drinking? We won’t lie: The only way to truly do so is by cutting back on booze. Abstaining from alcohol, even for just a few weeks, has been shown to meaningfully improve markers of gut health and function in both heavy and light drinkers.^24,25 

In addition to drinking less, here are a few ways to drink more responsibly that your microbiota—and your hangover poops—will thank you for:

• Spread out your drinks and add water: Research shows that reducing the amount of alcohol you consume in one sitting may positively impact your intestinal permeability and gut microbiome.^24,25 Drinking water with booze will also help speed up the recovery process and maintain microbial homeostasis.²⁶
• Opt for wine, cider, or beer: As we covered earlier, some drinks (like wine and fermented options) may have benefits for microbiome health. Beer also contains some gut-friendly compounds, though its carbonation might make you feel gassy and bloated.
• Eat food (especially carbs) with booze: “Never drink on an empty stomach” is gospel for a reason. Without food, booze moves quickly from your stomach to the small intestine and into your bloodstream—leading to a fast, intense surge of ethanol that your body will struggle to process. Food, particularly carbohydrates, will slow this absorption and reduce the risk of a rough morning.²³ 
• Avoid compounding gut disruptors: Sugar-rich and highly processed foods are well-known to disrupt the gut microbiome. Do your best to avoid them if your gut is already busy dealing with alcohol. Stimulants like caffeine may also make the urge to poop more intense, so lay off the espresso martinis to avoid being stuck in the bathroom.
• Refuel with fermented foods and probiotics: Consuming fermented foods, such as yogurt, can help restore gut microbiota balance that’s been disrupted by alcohol. Taking a probiotic supplement may also help ease alcohol-induced liver damage via the gut-liver axis, research suggests.²⁷
• Get your gut back on track: In the days after drinking, show your microbiome some love by getting plenty of exercise, eating a plant-rich, high-fiber diet, prioritizing sleep, and managing your stress levels. While it may be tempting to take an NSAID for any hangover symptoms, these can further disrupt the beneficial bacteria in your gut.²⁸

FAQs

Why is poop different after drinking alcohol?

Alcohol can cause diarrhea due to the way it disrupts the gut microbiome, irritates the gut barrier, impacts hormone production, and leads to dehydration and electrolyte imbalances. On the flipside, you may also feel constipated after a night of heavy drinking. 

What does alcohol do to your gut? 

Alcohol disrupts the balance of bacteria in the gut microbiome. It reduces the populations of beneficial bacteria in the gut while promoting the growth of harmful ones. This imbalance weakens the gut’s protective barrier, increasing intestinal permeability and allowing inflammatory toxins to enter the bloodstream. Over time, alcohol-induced liver damage can further impair gut health and function via the gut-liver axis.

How long does alcohol diarrhea last?

It totally depends on your weight, your gender, what you drank, and how much you drank (to name just a few factors). However, following gut-supportive protocols like eating some plants, sleeping, moving your body, and drinking plenty of water should help get your digestion back on track quickly.

The Key Insight

Alcohol can lead to diarrhea due to the way it aggravates the gastrointestinal tract and disrupts the gut microbiome.

There is no magic bullet for these symptoms; drinking less is the only way to completely avoid them. That said, pairing booze with a carb-heavy meal, fermented foods, and probiotics may help make your alcohol poops a little less of a buzzkill.