Part of our Asian Flush & Alcohol guide library.
Short answer: Alcohol speeds things up in your gut. It irritates the stomach and increases acid, it weakens the intestinal muscle movements that normally hold food back for digestion, and it can reduce how much water your intestines absorb, so stools come out sooner and looser. Sugary or sugar-free mixers, a heavy night of drinking and conditions such as irritable bowel syndrome (IBS) make it more likely. Most short bouts of diarrhea clear up on their own, but see a doctor if it lasts more than 2 days or you notice blood or black stools.
A night out, and the next morning you are running to the bathroom. It is common enough that people joke about it, but there are real reasons behind it. Here is what alcohol does to your stomach and intestines, why it often hits the morning after, which drinks and mixers make it worse, how to lower the odds, and when it is a sign to get checked.
What you'll learn
- Why alcohol gives some people diarrhea, step by step through the gut
- Why it often shows up the morning after drinking
- Whether beer, wine or liquor makes a difference, and how mixers play in
- What to do when it happens, and how to make it less likely
- Which symptoms mean you should talk to a doctor
Why do I get diarrhea after drinking?
Because alcohol changes how your stomach and intestines work, and several of those changes push toward loose stools. These are the main reasons we found in the research:
- Stomach irritation and acid. Alcohol directly irritates the stomach lining and increases acid release (NIAAA).
- Faster transit. In the small intestine, alcohol reduces the muscle movements that hold food back for digestion, while the movements that push it along stay the same, which can shorten transit time (Bode and Bode, 1997).
- Less water absorbed. In animal studies, a single dose of alcohol reduced the absorption of water and sodium in the small intestine, and regular drinking did the same in people (Bode and Bode, 1997).
- Acetaldehyde in the colon. Gut bacteria break down alcohol into acetaldehyde, which can build up in the colon and may contribute to diarrhea (Bode and Bode, 1997).
- Sugary or sugar-free mixers. Fructose in fruit juices and soft drinks, and sugar alcohols in sugar-free products, can cause diarrhea in some people (NIDDK), and alcohol may make the gut more sensitive to high-sugar drinks (Bode and Bode, 1997).
- Heavy drinking and gut conditions. In a diary study, binge drinking was linked with next-day diarrhea in women with IBS (Reding et al., 2013).
Usually it is a mix of these, which is why the same drink can affect you differently from one night to the next.
How does alcohol affect your gut?
Alcohol touches every part of the digestive tract it passes through, and each part reacts a little differently (Bode and Bode, 1997):
| Part of the gut | What alcohol does | How it can feel |
|---|---|---|
| Stomach | Beer and wine strongly increase stomach acid; drinks above about 15% alcohol slow stomach emptying. | Heartburn, fullness, gas, nausea |
| Small intestine | Fewer of the muscle movements that hold food back, and less water and sodium absorbed. | Faster, looser stools |
| Large intestine | Acetaldehyde from gut bacteria can build up; in healthy people, alcohol weakened muscle contractions in part of the rectum. | Urgency, loose stools |
| Gut lining (with regular heavy drinking) | Changes in gut bacteria and a leakier intestinal lining. | Ongoing digestive problems |
The gut lining row comes from a review of research on long-term heavy drinking (Bishehsari et al., 2017), not from a single night out. Acetaldehyde is the same compound behind Asian flush, although we found no study linking flushing itself to diarrhea.
Why do I get diarrhea the morning after drinking?
Because the effects of a heavy night carry over into the next day. Alcohol irritates the stomach and leaves you mildly dehydrated, and hangover symptoms can last 24 hours or longer (NIAAA). Meanwhile, food and drink that moved through your intestines faster than usual overnight reach the end of the line in the morning (Bode and Bode, 1997).
How much you drank seems to matter most. In a study of 166 women with IBS and 48 women without it, who kept daily diaries for about a month, binge drinking (4 or more drinks in a day) was linked with diarrhea, nausea, stomach pain and indigestion the next day in the women with IBS. Light and moderate drinking were not linked, or only weakly, and the healthy women did not show the pattern (Reding et al., 2013). For women, NIAAA defines binge drinking as 4 or more drinks in about two hours, and for men 5 or more (NIAAA).
Can beer or wine give you diarrhea more than liquor?
We found no study comparing diarrhea after beer, wine and liquor directly. What research does show is that drink type changes how the stomach responds: beer and wine strongly increase stomach acid, and by-products of fermentation in beer add to that, while whisky and cognac do not. Stronger drinks, above about 15% alcohol, instead slow stomach emptying, which can cause gas and fullness (Bode and Bode, 1997).
Volume matters too. A 12-ounce beer, a 5-ounce glass of wine and a 1.5-ounce shot of spirits each count as one standard drink (NIAAA), so a few pints add up to more liquid and often more mixers than the same alcohol as spirits. For how wine compares by the glass, see how much alcohol is in wine.
Why do I get diarrhea every time I drink?
If it happens even after a drink or two, something besides the alcohol may be involved. Common possibilities include (NIDDK):
- Mixers and sugars: fructose in juices and soft drinks, table sugar, or sugar alcohols in sugar-free mixers.
- Lactose: cream liqueurs and milky cocktails can trigger lactose intolerance symptoms within a few hours (NIDDK), and alcohol can interfere with lactase, the enzyme that digests lactose (Bode and Bode, 1997).
- IBS and other gut conditions: IBS, celiac disease, Crohn's disease and ulcerative colitis can all cause chronic diarrhea.
- Past surgery: surgery on the gallbladder, intestines, pancreas or stomach can lead to ongoing diarrhea.
- Regular heavy drinking: heavy alcohol use is one of the most common causes of chronic pancreatitis, which can cause diarrhea and greasy, foul-smelling stools (NIDDK).
If drinking reliably upsets your stomach, or you react to alcohol in other ways, see our guide to alcohol intolerance vs alcohol allergy, and mention the pattern to your doctor.
What should you do if you have diarrhea after drinking?
Focus on fluids. Replace lost fluids and electrolytes with water, broths, sports drinks or oral rehydration solutions, and go back to your normal food when your appetite returns (NIDDK). Older adults and people with diabetes, kidney disease or a weakened immune system should ask their doctor which fluids suit them (NIDDK).
Skip more alcohol until your stomach settles, since alcohol itself adds to fluid loss (NIAAA). If you are thinking about an over-the-counter diarrhea medicine, ask a pharmacist first, especially if you have been drinking or take other medicines. For more on fluids, see does alcohol dehydrate you?
How can you lower your chances of diarrhea after drinking?
Drinking less at a time is the change with the most support. In the IBS diary study, next-day symptoms tracked with binge drinking, not light drinking (Reding et al., 2013). Other practical steps:
- Count standard drinks, not glasses, so you know how much alcohol you are actually having (NIAAA).
- Watch the mixers. Juice, soda and sugar-free mixers can cause diarrhea on their own in some people (NIDDK).
- Track your triggers. Note what you drank, what you ate and how your stomach felt the next day; doctors use this kind of diary to find causes of diarrhea (NIDDK).
- Swap in alcohol-free rounds. Try a few of our easy mocktail recipes.
We found no study testing whether eating before drinking prevents diarrhea, although food does change how alcohol affects the stomach (Bode and Bode, 1997).
When should you see a doctor about diarrhea after drinking?
Talk with a doctor right away if you have any of these (NIDDK):
- Diarrhea lasting more than 2 days
- Six or more loose stools a day, or a high fever
- Stools that are black and tarry, or contain red blood or pus
- Severe pain in the abdomen or rectum, or frequent vomiting
- Signs of dehydration, such as extreme thirst, dark urine, urinating less, or feeling dizzy or lightheaded
- A change in mental state, such as irritability or lack of energy
Seek care right away for severe or worsening upper abdominal pain, especially if it spreads to your back or comes with fever, vomiting or yellowing of the skin or eyes, which can be signs of pancreatitis (NIDDK). If you are pregnant, over 65, taking antibiotics or have a weakened immune system, stay in touch with your doctor whenever you have diarrhea (NIDDK).
What about diarrhea after drinking coffee, milk or juice?
Those have their own causes. Milk can cause diarrhea within a few hours in people with lactose intolerance (NIDDK). Fruit juices and soft drinks contain fructose, and some people cannot digest it well (NIDDK). Coffee has its own effects on the gut; see why does coffee make you poop?
Common myths (quick reality check)
Myth: Diarrhea after drinking means your body is flushing out toxins. Reality: It reflects what alcohol does to your stomach and intestines, such as faster transit and less water absorbed (Bode and Bode, 1997). It is not a detox.
Myth: Liquor is always easier on your stomach than beer. Reality: Spirits do not raise stomach acid the way beer and wine do, but drinks above about 15% alcohol slow stomach emptying, which can cause gas and discomfort (Bode and Bode, 1997).
Myth: Everyone gets it, so it is not worth mentioning to a doctor. Reality: In one diary study, drinking was linked with next-day gut symptoms in women with IBS but not in healthy women (Reding et al., 2013). Frequent symptoms are worth checking.
Frequently asked questions (FAQ)
Why does alcohol make you poop the next day?
Alcohol speeds up how food moves through the small intestine, reduces water absorption and irritates the stomach. After a heavy night, those effects often show up the next morning.
Is diarrhea after drinking normal?
It is a known effect of alcohol on the gut, especially after heavy drinking. If it happens every time you drink, even after small amounts, talk to a doctor about other causes such as IBS or a food intolerance.
How long does diarrhea after drinking last?
Most short bouts of diarrhea go away on their own. Talk with a doctor if it lasts more than 2 days, or if you have blood in your stool, a high fever or signs of dehydration.
Can beer give you diarrhea?
It can. Beer strongly increases stomach acid, and large amounts mean more liquid and alcohol moving through the gut. No study has compared diarrhea after beer, wine and liquor directly.
Does drinking on an empty stomach cause diarrhea?
We found no study testing this directly. Food changes how alcohol affects the stomach, but the main factors linked to diarrhea are how much you drink and what you mix it with.
What should I drink when I have diarrhea after drinking?
Water, broths, sports drinks or oral rehydration solutions help replace lost fluids and electrolytes. Skip more alcohol until your stomach settles.
Is blood in my stool after drinking serious?
It can be. Stools that are black and tarry or contain red blood are a reason to talk with a doctor right away.
Related guides
- Does alcohol dehydrate you?
- How long does a hangover last?
- Which alcohol gives the least hangover?
- Alcohol intolerance vs alcohol allergy
- Is alcohol a blood thinner?
- Why does coffee make you poop?
- Alcohol and liver disease
- Why do Asians get Asian flush?
Disclaimer and when to seek help
This article is for general education and is not medical advice. These statements have not been evaluated by the Food and Drug Administration. Our products are not intended to diagnose, treat, cure, or prevent any disease. Talk to your doctor if diarrhea lasts more than 2 days, keeps coming back, or comes with blood, black stools, high fever, severe pain or signs of dehydration. Ask a pharmacist before taking any over-the-counter medicine, especially after drinking or if you take other medicines. If you have concerns about your drinking, talk to your health care provider.
References
- Bode C, Bode JC. "Alcohol's role in gastrointestinal tract disorders." Alcohol Health and Research World, 1997;21(1):76-83. PMC6826790
- Reding KW, Cain KC, Jarrett ME, Eugenio MD, Heitkemper MM. "Relationship between patterns of alcohol consumption and gastrointestinal symptoms among patients with irritable bowel syndrome." The American Journal of Gastroenterology, 2013;108(2):270-276. doi:10.1038/ajg.2012.414
- Bishehsari F, et al. "Alcohol and gut-derived inflammation." Alcohol Research: Current Reviews, 2017;38(2):163-171. doi:10.35946/arcr.v38.2.02
- National Institute of Diabetes and Digestive and Kidney Diseases. "Symptoms & Causes of Diarrhea" Last reviewed September 2024.
- National Institute of Diabetes and Digestive and Kidney Diseases. "Treatment of Diarrhea" Last reviewed September 2024.
- National Institute of Diabetes and Digestive and Kidney Diseases. "Symptoms & Causes of Lactose Intolerance"
- National Institute of Diabetes and Digestive and Kidney Diseases. "Symptoms & Causes of Pancreatitis"
- National Institute on Alcohol Abuse and Alcoholism. "Hangovers"
- National Institute on Alcohol Abuse and Alcoholism. "Understanding Alcohol Drinking Patterns"
- National Institute on Alcohol Abuse and Alcoholism. "What Is A Standard Drink?"
