Why do poops smell?


What Causes Foul-Smelling Stools?

Changes in diet are a common cause of foul-smelling stool. Additional causes include the following:


Malabsorption is also a common cause of foul-smelling stool.

Malabsorption occurs when your body is unable to absorb the proper amount of nutrients from the food you eat. This generally occurs when there’s an infection or disease that prevents your intestines from absorbing nutrients from your food.

Common causes of malabsorption include:

  • celiac disease, which is a reaction to gluten that damages the lining of the small intestine and prevents proper absorption of nutrients
  • inflammatory bowel disease (IBD), such as Crohn’s disease or ulcerative colitis
  • carbohydrate intolerance, which is an inability to process sugars and starches completely
  • dairy protein intolerance
  • food allergies

If you haveIBD, eating certain foods will cause your intestines to become inflamed. People with IBD often complain of foul-smelling diarrhea or constipation. People with IBD also have flatulence after eating certain foods. This flatulence may have a foul smell.


Infections that affect the intestines may also cause foul-smelling stools. Gastroenteritis, an inflammation of the stomach and intestines, can occur after eating food contaminated with:

  • bacteria, such as E. coli or Salmonella
  • viruses
  • parasites

Soon after developing the infection, you may experience abdominal cramps and then have foul-smelling, runny stools.

Medications and supplements

Certain medications may cause gastrointestinal discomfort and diarrhea.

Taking some over-the-counter multivitamins may also cause foul-smelling stools if you’re allergic to the supplements’ ingredients. After a course of antibiotics, you may have foul-smelling stools until your normal bacterial flora is restored.

Foul-smelling diarrhea can be a side effect of taking more than the recommended daily allowance of a multivitamin or any single vitamin or mineral.

Diarrhea associated with a multivitamin or more medication than the recommended dosage is the sign of a medical emergency. Getting too much of any of these vitamins can have life-threatening side effects:

  • vitamin A
  • vitamin D
  • vitamin E
  • vitamin K

Other conditions

Other conditions that can cause foul-smelling stools include chronic pancreatitis, cystic fibrosis, and short bowel syndrome.


What is giardiasis?

Giardiasis is an infection caused by a parasite called Giardia. It causes diarrhea. It is passed on through oral contact with infected feces. You can get the parasite by eating food or drinking water that contains infected feces. When you travel, make sure not to drink water that may be unsafe.

Giardiasis a common intestinal parasite. It is most prevalent in countries with poor sanitary conditions, poor water quality control, and overcrowding. However, it is also a common cause of parasitic infection in the U.S. Hikers and campers who drink water from streams and other potentially contaminated sources are often infected.

What causes giardiasis?

The parasite that causes giardiasis lives in two stages:

  • Trophozoites (the active form inside the body)
  • Cysts (the resting stage that enables the parasite to survive outside the body)

Infection begins when the cysts are taken in through contaminated food or water. Stomach acid activates the cysts and the trophozoites are released. They attach to the lining of the small intestine and reproduce. Cysts form in the lower intestines and are then passed in the feces.

The parasite may be passed from person-to-person by contact with infected feces, or through consuming contaminated food or water.

What are symptoms of giardiasis?

Symptoms of giardiasis may include:

  • Explosive, watery, foul-smelling stools
  • Greasy stools that tend to float
  • Bloating
  • Nausea
  • Loss of appetite
  • Abdominal (belly) pain
  • Excessive gas
  • Fatigue

The time between infection and the start of symptoms is usually from 1 to 2 weeks. Some infected people have very mild symptoms or no symptoms at all. The symptoms of giardiasis are a lot like those of other gastrointestinal diseases. See a healthcare provider for diagnosis.

How is giardiasis diagnosed?

Diagnosis of giardiasis is made by testing stool samples in a lab. Several stool samples may be needed at different times. If you think you may have this illness, contact your healthcare provider for advice.

How is giardiasis treated?

Giardiasis may be treated with prescription medicines. Specific treatment for giardiasis will be determined by your healthcare provider based on:

  • How old you are
  • Your overall health and medical history
  • How sick you are
  • How well you can handle specific medicines, procedures, or therapies
  • How long the condition is expected to last
  • Your opinion or preference

Several medicines can be used to treat the infection. Effective treatments include metronidazole, tinidazole, and nitazoxanide.

What are the complications of giardiasis?

If the infection is not treated and persists, you may not be able to absorb nutrients. It can also cause unintended weight loss.

Can giardiasis be prevented?

You can prevent giardiasis by practicing good personal hygiene. Proper hygiene when caring for those who may be infected with the parasite is also important. When visiting in an area where giardiasis may exist:

  • Drink only boiled water or bottled water or drinks.
  • Avoid ice and beverages made from tap water.
  • Do not eat locally grown uncooked or unpeeled fruits and vegetables.

When should I call my healthcare provider?

Call your healthcare provider if:

  • Your symptoms get worse or you have new symptoms
  • You lose your appetite and start to lose weight
  • You become dehydrated from prolonged diarrhea

Key points about giardiasis

  • Giardiasis is an infection caused by a parasite called Giardia. It causes diarrhea.
    Symptoms include explosive, watery, greasy, foul-smelling stools, bloating, nausea, pain, gas, fatigue, and loss of appetite.
  • Several medicines are available that cure the infection.
  • Prevention includes good personal hygiene, and avoiding drinking water, fruits, and vegetables that may be contaminated with the parasite.

Next steps

Tips to help you get the most from a visit to your healthcare provider:

  • Know the reason for your visit and what you want to happen.
  • Before your visit, write down questions you want answered.
  • Bring someone with you to help you ask questions and remember what your provider tells you.
  • At the visit, write down the name of a new diagnosis, and any new medicines, treatments, or tests. Also write down any new instructions your provider gives you.
  • Know why a new medicine or treatment is prescribed, and how it will help you. Also know what the side effects are.
  • Ask if your condition can be treated in other ways.
  • Know why a test or procedure is recommended and what the results could mean.
  • Know what to expect if you do not take the medicine or have the test or procedure.
  • If you have a follow-up appointment, write down the date, time, and purpose for that visit.
  • Know how you can contact your provider if you have questions.

Warning Signs in Your Toilet, Pt 1 (5:12)

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When trying to figure out the significance of a symptom you may be having, it’s helpful to think in terms of what’s the most likely diagnosis and what’s the most lethal. Hopefully they are not the same. For example, the most likely cause of red blood in the stool is hemorrhoids, but the most lethal is colon cancer.

From This Episode:

Are Your Pee and Poop Normal?

Watch: How to Poop Perfectly

Taking a close look at your stool can tell you a lot about what’s going on in your intestines and can lead you to make the right changes to improve your digestive and overall health. If you know what to look for, it’s like reading tea leaves! I tell my patients that if they pay close attention to what’s going on in the bowl, they might not need my services.

Here’s a guide to some of the most likely – and most lethal – conditions that can lead to changes in the shape, size, smell and shade of your stool.


Insufficient fiber in the diet, diverticulosis, bowel spasm or excessive straining are common causes of a change in stool shape. Diverticulosis causes pothole-like craters in the lining of the colon, as well as a narrowing of the internal diameter of the colon due to wall thickening. The result is narrow, pellet-like stools that often fall apart in the bowl and can be difficult to expel. Other associated symptoms of diverticulosis include a dull ache in the lower abdomen, a feeling of incomplete evacuation even though you may be having multiple bowel movements, and lots of gas and bloating. Endometriosis, uterine fibroids, masses in the abdomen or tumors in other organs, like the ovaries or bladder, can cause thin stools due to external compression of the colon. Colon cancer definitely needs to be excluded by a colonoscopy in anyone experiencing new onset of pencil-thin stools, which can occur as a tumor gets larger and grows inward, reducing the colonic diameter.

WATCH: Why Do People Poop Sitting Down?


Size matters. Small, hard stools are typical in people eating a low-fiber Western diet, and are associated with a higher risk for ultimately developing diverticulosis and colon cancer. Constipation is often associated with small, difficult-to-pass stools, and people suffering from constipation-predominant irritable bowel syndrome (IBS) are particularly prone to having small stools. A high-fiber diet or regular use of a bulking agent like psyllium husk will lead to larger, softer stools in most people, making defecation easier. Even though a fiber-deficient diet is the most likely culprit, colon cancer is again on the list as most lethal.


The odor of your stool is highly dependent on a number of factors, including how long it’s been sitting in your colon, your diet, medications you may be taking and, in some cases, the presence of infection. Bacterial imbalance (dysbiosis) in the GI tract and undigested fat can also lead to a change in odor.

The most common cause of smelly stool is bacterial fermentation of the food in your intestines that produces foul-smelling sulfide compounds. Antibiotics can also change the smell of stool and give it a medicinal odor. More lethal causes of malodorous stool, and fortunately much less common, include inflammation of the pancreas (pancreatitis) and pancreatic cancer. Both these conditions can result in floating, foul-smelling stool with an oily sheen.

WATCH: The Poop Primer

Diseases that cause malabsorption of nutrients like Crohn’s, celiac disease and cystic fibrosis can also lead to foul-smelling stool. Infection with parasites such as giardia lamblia can cause stool to have a very unpleasant odor.

New onset of diarrhea associated with a foul odor should prompt an evaluation for infection, whereas fat in the stool associated with a foul odor should raise concerns about malabsorption or pancreatic disorders. For most people, smelly stool is simply a byproduct of the beans they had for dinner the night before.


The color of stool can vary dramatically and can also be a clue as to whether various disease states are present.

Normal stool is brown due to its composition: bacteria, water, bile, bilirubin, broken-down red blood celIs and indigestible plant matter like cellulose, along with small amounts of protein and fat.

LEARN MORE: Use This Printable Poop Log

Red stool is most worrisome as it indicates bleeding in the lower GI tract from conditions like hemorrhoids or diverticulosis, or more serious conditions like rectal cancer. Red stool can also be caused by ingesting red food coloring or beets. While it should always be reported, it’s not always an ominous sign.

Green stool can occur with rapid transit through the intestines where bile doesn’t have a chance to be broken down to its final brown color. Green can also be a sign of Crohn’s disease, antibiotic use, ingestion of leafy greens or iron therapy.

Yellow stool can be the result of gallbladder dysfunction which causes improper handling of bile. Infection with giardia lamblia produces a characteristic yellow diarrhea. In addition to causing diarrhea, different types of infection in the GI tract, whether viral, bacterial or parasitic, may cause changes in stool color.

White stool can be a sign of fat malabsorption, as with pancreatitis and pancreatic cancer, but barium used for X-rays can also give the same appearance. Mucus in the stool can give it a whitish appearance and may be due to inflammation or benign conditions like IBS.

WATCH: How to Poop Perfectly

Black stool should trigger a search for bleeding from the upper part of the GI tract (esophagus, stomach or small intestine), but can also be seen with iron therapy, heavy meat consumption, and bismuth-containing compounds.

Light-appearing clay-colored stools are characteristic of liver disease and decreased bile output, but can also be caused by antacids containing aluminum hydroxide. Vitamins and supplements commonly cause changes in urine color but may also change stool color.

For Dr. Oz’s Poop Color Chart, .

Your Most Burning Poop Questions, Answered

How Often Should You Go?

Stool frequency is regulated by the amount of fiber and fluid you drink. Exercise and staying active also plays a role by encouraging healthy bowel movements. That means the frequency of bowel movements can vary quite a bit and still be considered normal, ranging from three bowel movements a day to three a week. The important thing to know is what’s normal for you and to pay attention to any notable changes.

Constipation occurs when you have fewer bowel movements than usual. Stools will typically be harder and dryer than normal. Left untreated, fecal impaction may develop, according to the National Cancer Institute (NCI). This is when you’re unable to pass dry, hard stool.

Back and stomach pain are other possible signs of fecal impaction. This often occurs when people take prescription painkillers or if they’ve been sedentary for long periods of time. Abusing high doses of laxatives can also lead to fecal impaction. An enema can be used to treat the problem if necessary.

On the flip side, diarrhea stools are more loose and watery and more frequent than normal. Diarrhea is more likely to be caused by an infection. These conditions can alternate or be persistent and include other symptoms, such as belly pain and bloating, which may indicate an underlying health issue, such as irritable bowel syndrome (IBS), according to the U.S. Department of Health and Human Services.

RELATED: Seriously Bloated: Warning Signs You Shouldn’t Ignore

What Color Should My Poop Be?

The brown coloration of a healthy stool comes from the bile released by the liver changing colors as it travels through your intestines. Poop that’s a color other than brown could point to a health issue:

  • Black Stools While taking a vitamin that contains iron or medication that contains bismuth subsalicylate can cause this, black stools can also signal a more serious problem. “Dark black stools could be caused by bleeding in the stomach, a duodenal ulcer, or a tumor,” says Dr. Loftus.
  • White Stools On the other hand, a white color can be worrisome too. Loftus explains that this can occur due to a lack of bile and may indicate a blockage in the bile duct. This may be because of a problem in the liver or even a bile duct cancer.
  • Red Stools Certain foods, such as beets, could turn your poop red. But it could also mean that blood is coming from the lower area of the colon, which is a sign of inflammatory bowel disease (IBD). Blood in your feces could also be caused by hemorrhoids or colon cancer.
  • Green Stools Eating vegetables, such as leafy greens, can result in green colored stools. Taking iron supplements can also turn your poop green. One possible problem with green stools is that when bile passes through the intestines too quickly, it stays green along with your poop, according to the Gastrointestinal Society, the Canadian Society of Intestinal Research.
  • Gray Stools Light-colored stools may related to a liver or gallbladder problem. Other possible causes for stools that appears pale, gray, or clay-colored include viral hepatitis, gallstones, or alcoholic hepatitis.

Why Does Poop Sometimes Float?

Normally, your stool should sink to the bottom of the toilet. This is because the contents of feces are typically denser than water. An intestinal infection or changes in your diet that introduce more gas into your digestive system, such as a high-fiber or high-fat diet, can cause stools to float. People with GI conditions that affect fat absorption, such as celiac disease or Crohn’s disease, often have floating stools.

How Should Healthy Poop Smell?

It’s perfectly normal for poop to have an unpleasant odor. The smell comes from bacteria in the colon that help break down digested food. Poop may smell different due to changes in your diet. But very foul-smelling feces can be a sign of a serious medical condition, such as:

  • Celiac disease
  • Crohn’s disease
  • Pancreatitis
  • Ulcerative colitis
  • Infection
  • Malabsorption

Why Does It Hurt When I Poop?

Bowel movements should pass easily with little straining. There are a number of reasons why pooping could be uncomfortable. The most common reason is inadequate fiber intake. According to the Academy of Nutrition and Dietetics, the recommended daily amount of fiber for women is 25 grams (g); for men it’s 38 g. After age 50, though, fiber intake recommendations decrease to 21 g for women and 30 g for men.

Difficulty pooping could also be the result anal fissures, tears in the anus, as well as hemorrhoids. Crohn’s disease, ulcerative colitis, or other conditions that trigger inflammation along the GI tract can also lead to painful bowel movements. Pain that’s severe can be a sign that a tumor is blocking the anus or rectum.

It’s important to let your doctor know if you have blood in your stool, black stool, pale stool, fever, cramps, mucus in your stool, pain, floating stool, or weight loss. Knowing the facts about feces is no joke.

Additional reporting by Tuan Nguyen

9 things you probably didn’t know about poo

Unless you’re a parent of a young child, or a traveller in somewhere like Bali or India, poo tends not to be a topic of conversation.

But that can mean you miss out on some fabulously interesting – and pretty damn useful – toilet trivia.

It might not enhance your dinner party chit chat, but there’s much you need to know about poo.

So fasten your seatbelt. Here are some key points on your journey of discovery.

1. Poo is mostly water

Poo might look solid (unless you’ve got a dose of the runs) but in fact your stools are up to 75 per cent water. And of the solid matter, around a third is actually dead bacteria. Another third or so is indigestible food matter (which includes the outside of corn kernels you see in there). The rest is cholesterol and fats, protein and inorganic substances like iron phosphate. These are all collected along the digestive tract from your mouth to your bottom.

2. Poo is like Christmas

No we’re not talking about the colloquial term for the effect your in-laws have on your mood when they arrive on Christmas Day. But poo does come from something red and green. Poo gets its brown colour from a chemical that gets released when red blood cells are broken down in our bodies. The chemical travels to the gut via bile, a green digestive fluid produced by the liver. But during the digestion process, bile mixes with what we have eaten, and it changes colour from green to brown as it is modified by bacteria as it travels to our colon.

3. Poo can be like a rainbow

What you eat can affect the colour of your stools, though. So can certain health conditions and medications. The end result can be green, pale yellow, grey, black, or maroon. A bright green poo can indicate a quick transition through the bowel where the bile has had no time to change to brown. This can happen if you have diarrhoea, for instance. Pale brown or yellowish poo may indicate you are producing too little in the way of bile salts. Persistent greyish white or very pale yellow poo can also indicate problems with organs like the liver.

4. If you see red, it’s a red flag

The most important thing poo can let us know about our health is whether we have a bowel tumour. Bowel tumours often bleed so you should always talk to your doctor if you see any blood after you poo – either on the outside of stools, on toilet paper after you wipe or in the bottom of the toilet bowl.

5. But not all red flags mean bowel cancer

Haemorrhoids, anal fissures, bowel polyps, peptic ulcers and a range of other digestive diseases can also cause bleeding on toilet paper or in the toilet bowl. Likewise, black, dark red or maroon poo may also be the result of taking iron tablets or gorging yourself on licorice or blueberries. Sometimes you can have more than one thing going on. Your doctor is the best person to investigate.

6. It’s a jungle in there (or is it a butcher shop?)

The Bristol stool scale or Bristol stool chart is a medical aid designed to classify the form of human faeces into seven categories. (Wikimedia Commons/CC BY-SA 3.0)

The Bristol stool scale or Bristol stool chart is a medical aid designed to classify the form of human faeces into seven categories.

Wikimedia Commons/CC BY-SA 3.0


Rabbit pellets, snakes, furry bits … you’d be forgiven for thinking there was a jungle in your bowel. But it’s a fact that bowel motions come in a variety of shapes, sizes and consistencies, and this has been described in something called the Bristol Stool Scale, first published in 1997.

The chart classifies human poo into seven categories and was designed as a tool to ascertain a person’s bowel transit time – the time it takes for food to pass through the digestive tract. But others like the Gut Foundation of Australia’s president prefer to make allusions to small goods when discussing number twos. Dr Terry Bolin says you need to eat enough fibre to avoid constipation: “The aim of everyone is to produce a sausage a day at least – preferably a kransky rather than a chipolata.”

7. You don’t have to go every day

Hands up if you’ve got an elderly relative who loves to talk about their bowel habits at family gatherings? Chances are one thing you’ll hear is that it’s vital you poo daily. In fact, bowel behaviour is highly variable both from one individual to the next and it can even vary from one day to the next for the same person. Somewhere between three times a day and three times a week seems to be the ‘normal’ range, according to a 2010 Scandinavian study.

8. Laxatives can be your friend (just not your bestie)

A belief daily bowel movements are necessary for good health isn’t always entirely harmless. It can lead some middle-aged or older people who begin using laxatives when constipated to continue to overuse them, researchers from the University of Dakota said in a 2010 review article in the journal Drugs. Such individuals form one of four key groups who misuse or abuse laxatives – a habit that can be associated with medical problems including changes to electrolytes (vital chemicals in the body) and the level of acidity or alkalinity of body fluids. These problems can affect the kidneys and cardiovascular systems and may become life-threatening.

9. Doing a poo (or farting without doing a poo) is a masterpiece of finely controlled bodily engineering

Poo passes out of your body through your anus and its passage is controlled by a muscular area called the anal sphincter. The cells lining the anus are very sensitive and can sense the difference between poo and gas in your rectum, allowing you to pass gas when you have wind without releasing any liquid or solid matter from your rectum. This feat so impressed one doctor that he wrote an ode in praise of the “magnificent” anal sphincter in the American Journal of Proctology in 1961: “If you place into your cupped hands a mixture of fluid, solid, and gas and then try to let only the gas escape through an opening at the bottom, you will fail. Yet the anal sphincter can do it. No other muscle in the body is such a protector of our dignity, yet so ready to come to our relief.”

Poo: You might also like…

  • What your poo can tell you
  • Do you need to poo every day?
  • Lifting the lid on farting and flatulence

6 Reasons Why Your Poop Smells So Bad

Anyone who’s had to bust out air freshener after a number two session knows that some visits to the throne can be more potent than others. While it’s no secret that poop is supposed to smell bad, a next-level nasty aroma could be a sign that something’s off with your digestive system. Look into one or more of these possible culprits:

You Eat a Lot of Meat

When you eat foods that are high in sulfur-such as meats, dairy, garlic, and cruciferous veggies (think: broccoli, cabbage, kale)-your gut works overtime to digest them and produces a larger amount of the gasses that make your poop smell. “Even with normal digestion, these foods will lend an eggy aroma to stool,” says Anish Sheth, M.D., author of What’s Your Poo Telling You? Translation: Avoid sulfur-rich foods on a first date.

You’re Lactose Intolerant

If things get explosive every time you dig into your fave ice cream, you could be lactose intolerant. “Lactase is an enzyme that breaks lactose down to make it easier for your body to digest,” explains Niket Sonpal, M.D., assistant professor at Touro College of Osteopathic Medicine. “If you lack the lactase enzyme or produce an insufficient amount, bacteria in your large intestine causes the undigested lactose to ferment and produce foul-smelling gas and stools.” Put the kibosh on the discomfort (and aroma) by cutting back on dairy products, switching to lactose-free options, or popping lactase enzyme tablets (such as Lactaid) just before a meal or snack.

You Ate Too Much Junk Food

Eating fatty or processed, sugary foods can make your poop smell awful, says Gina Sam, M.D., director of the Gastrointestinal Motility Center at Mount Sinai Hospital. Some people lack the digestive enzymes necessary to fully break down fats, which can delay the digestion process. The longer the food sits around, the more digestive gasses your bod will produce, which will make your number two sessions that much smellier. Meanwhile, processed foods contain oodles of synthetic ingredients that can give the digestive system a hard time. Best to steer clear of these culprit foods as much as possible, says Sheth. (Try these 15 Junk Food Alternatives.)

You’re Taking Medication

“Many times medications are coated with indigestible sugars such as sorbitol, which can ferment and make your poop smell funky,” says Sonpal. “If you note running to the bathroom after starting a new medication, it may be worth talking to your doctor about finding an alternative formulation.”

Your Gut’s Out of Whack

The over-arching theme for foul-smelling poop is malabsorption, says Sonpal, which occurs when your body’s unable to absorb the proper amount of nutrients from the foods you eat. “If you’re unable to break down and digest certain nutrients, they rot and smell really bad on the way out,” he explains. This can be caused by any number of things, such as a gluten allergy or a bacterial overgrowth in your intestines. “Most conditions that cause foul-smelling stools are treatable,” says Sonpal. “However, some diseases may require lifelong changes to your diet, or medications to control bowel movements and pain.” (Here’s How Your Gut Affects Your Health and Happiness.)

  • By Krissy Brady

Have you examined your poop today?


Are you going to the bathroom more than 3 times per day or fewer than 3 times per week? Going too much can signify diarrhea, and going too little can signify constipation. We will talk about both of these disorders in upcoming articles in this poop series. In the meantime, common causes of diarrhea include irritable bowel syndrome (IBS), inflammatory bowel diseases (IBD) such as Crohn’s and ulcerative colitis, food sensitivities (especially to gluten and lactose), parasites, and stress. Common causes of constipation include eating too little fiber, gut dysbiosis (overgrowth of “bad” bacteria), and dehydration.

How often you’re going is less important than how easy it is for you to go. Pooping should never be painful or cause you to strain. Moving your bowels should take no more effort than urinating or passing gas.

The color of stool is affected by many factors, but especially by what you eat. Poop should normally be light- to dark-brown. This color comes from bile and bilirubin from dead red blood cells.3 Stools that are green can be caused by excess bile. In contrast, insufficient bile causes stools that are pale or gray, due to problems with the liver, gallbladder, or pancreas.3 Black or red stools are a sign of bleeding in the upper or lower GI tract, and should always be reported to a doctor if it lasts longer than a day. Other colors including blue, silver, and purple/violet have been seen with other serious medical conditions.


Let’s be honest…nobody’s poop smells like roses. But certain odors are associated with certain conditions. Especially foul-smelling stools can occur with IBD, pancreatitis, malabsorption, and bacterial overgrowth, among other conditions.4 A strong sulfur smell indicates the presence of hydrogen sulfide gas. A “vomity” smell can indicate that your food is not being digested as well as it should.

And, speaking of malodorous things, what about gas? Passing gas (flatulence) is normal. Not only is it normal, but it’s also a good sign that your gut bacteria are doing their job. But normal gas should be odorless, so if your farts smell bad, that’s a sure sign that something isn’t working right in your gut.

Stay tuned for the next article in our Poop Series. We’ll talk more about constipation and what you can do to help.

Better Gut Tip: Next time you poop, take a good look to determine what its texture, frequency, color, and odor are trying to tell you!

Black or tarry stools

Your provider will take a medical history and perform a physical exam. The exam will focus on your abdomen.

You may be asked the following questions:

  • Are you taking blood thinners, such as aspirin, warfarin or clopidogrel, or similar medicines? Are you taking an NSAID, such as ibuprofen or naproxen?
  • Have you had any trauma or swallowed a foreign object accidentally?
  • Have you eaten black licorice, lead, Pepto-Bismol, or blueberries?
  • Have you had more than one episode of blood in your stool? Is every stool this way?
  • Have you lost any weight recently?
  • Is there blood on the toilet paper only?
  • What color is the stool?
  • When did the problem develop?
  • What other symptoms are present (abdominal pain, vomiting blood, bloating, excessive gas, diarrhea, or fever)?

You may need to have one or more tests to look for the cause:

  • Angiography
  • Bleeding scan (nuclear medicine)
  • Blood studies, including a complete blood count (CBC) and differential, serum chemistries, clotting studies
  • Colonoscopy
  • Esophagogastroduodenoscopy or EGD
  • Stool culture
  • Tests for the presence of Helicobacter pylori infection
  • Capsule endoscopy (a pill with a built in camera that takes a video of the small intestine)
  • Double balloon enteroscopy (a scope that can reach the parts of the small intestine that are not able to be reached with EGD or colonoscopy)

Severe cases of bleeding that cause excessive blood loss and a drop in blood pressure may require surgery or hospitalization.

This article was medically reviewed by Leila Kia, M.D., a board-certified gastroenterologist and member of the Prevention Medical Review Board, on November 7, 2019.

Chances are, you’ve experienced number two sessions so potent that busting out an air freshener was practically mandatory. Sometimes the culprit is super-obvious—a pint of ice cream here, some spicy street food there. Other times, not so much. And when it seems like your poop has become extra smelly out of nowhere, it’s hard not to freak out.

“Poop smells because of bacteria and their byproducts of digestion,” says New York City-based gastroenterologist Samantha Nazareth, M.D. “If there’s a divergence in smell (let’s say one occurrence), then it could be from something you ate or drank. But if it’s consistently abnormal (as in, different from what your poop usually smells like), then there may be something else going on.”

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Scent changes that are accompanied by other iffy symptoms, such as cramping, gastrointestinal pain, weight loss, or changes in how your poop looks (think: floating, sticky, bloody) warrant evaluation by your doctor.

As for what might be causing that extra-smelly poop of yours, below are several possible culprits—and exactly what to do about them.

1. You’ve been eating sulfur-rich foods.

Sulfur-rich foods—a la meat, cheese, and cruciferous veggies (Brussels sprouts, broccoli, cauliflower)—are harder to digest than other foods, so your gut has to work overtime to get the job done.

“During this process, more gasses are released—hence the more pungent smell,” says California-based functional medicine physician Yeral Patel, M.D. If your diet is heavy on foods that are high in sulfur, consider either shrinking your servings, or avoid combining several sulfur-rich foods in single meals.

KuvonaGetty Images

2. A food intolerance could be stirring up trouble.

If you find that certain foods cause foul-smelling gas or loose, smelly poop, you might have an underlying intolerance. “A common one is lactose, but people can also have fructose and other carbohydrate intolerances,” says Dr. Nazareth. “The sugar component of the food item isn’t being broken down by the gut.” (Think of the way something smells if it’s left on the kitchen counter and rots.)

Track your food intake for a week or two, and keep tabs on the meals and snacks that end with dicey trips to the throne. You might find that certain ingredients play a starring role in your digestive debauchery and may need to be taken off the menu. If the thought of parting with these foods causes you to experience a real-life breakup montage, however, you can always find out from your doctor if certain digestive enzymes can give your gut a hand.

3. You downed one too many cocktails.

The kind of alcohol and how much of it you drink can both affect your poop. Alcohol itself is high in sulfates, which the bugs in your gut convert into stinky sulfide gasses. It also changes how fast your digestion works: “Sometimes, when you’ve consumed too much alcohol, the colon works extra hard to excrete the excess waste, flushing it more quickly through your system,” says Dr. Patel.

The excess alcohol, combined with any undigested waste that exits along with it, is what creates that lovely morning-after stench. Besides drinking less or spreading out your cocktails, make sure to drink a lot of water, as dehydration from boozing it up can also affect the rankness of your poop.

4. …or a pile of junk food.

“Highly processed and sugary foods are all difficult to digest,” says Dr. Patel. “As a result, the digestion process takes longer, food remains in your system longer, and the body produces more gasses.”

Plus, junk food is usually high in fat, and sometimes the body can’t break down and absorb the excess properly, says Dr. Nazareth. The fat then passes through undigested and causes smelly poop. To top it off, processed foods contain quite a few iffy chemicals and additives that can give your digestive system attitude, so best to scale back on your intake as much as possible.

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5. It’s a side effect of your medication or supplements.

Many medications are coated with substances, such as sorbitol, that can ferment in your gut, causing digestive drama and—you guessed it—smelly poop. Ditto for vitamins and supplements. Consuming even slightly more than the recommended amount can wreak havoc with the bowels too, says Dr. Patel, so make sure you discuss this with your doctor before taking, and ask whether there are steps you can take to avoid disruptions to your digestion.

6. You’re constipated.

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The longer poop takes to mosey its way through your colon, the longer it has to ferment and cause a stink. For situational constipation (say, due to traveling or not sleeping), try increasing your water intake and eating easily-digestible foods (baby food consistency), suggests Dr. Nazareth. “There are also stool softeners, fiber supplements, and OTC laxatives,” she adds. But if you’re still backed up and are depending on these OTCs to go to the bathroom, it’s time to check in with your doctor for a consult.

7. A recent switch in your diet could be to blame.

For people on a high-protein or high-fat diet where a lot of meats and cheeses are consumed, the smell of your poop will inevitably intensify. “Most people are used to getting fiber by way of the carbs in their diet, but when those are eliminated, many experience constipation,” says Dr. Patel. “Because the body produces more smelly gasses the longer the stool sits without being eliminated, the smell is unusually bad when it finally comes out.” Another side effect of consuming high-fat meats is that the body can’t deal with the excess fat, and smelly, putrid diarrhea results.

To get the number two train back on the rails, try adding high-fiber foods to your diet that are also considered keto-friendly, such as non-starchy veggies, avocados, and nuts (and don’t forget to guzzle more water as you increase your fiber quota to keep things moving.)

8. You have (or had) an infection.

Gut infections can be viral, bacterial, or parasitic in nature, and cause the gastrointestinal tract to become inflamed—symptoms can include abdominal pain, vomiting, and smelly diarrhea. Your doctor can test your poop to determine exactly the type of infection you have and offer up an appropriate treatment option.

But take note: If you’re prescribed antibiotics, this can also result in foul-smelling poop. The medications typically upset the dynamic between the good and bad bacteria in the gut, says Dr. Patel, so make sure to ask for ways to keep your gut flora happy during treatment.

9. Your overall gut health needs work.

The common thread underlying your poop problems is what docs call malabsorption, where the body can’t absorb certain nutrients properly (such as carbs, protein, or fats), and cause the undigested nutrients to smell pretty foul on the way out. “Some of the illnesses these symptoms can indicate are celiac disease, pancreatitis, Crohn’s disease, or inflammatory bowel disorder,” says Dr. Patel. “These are all conditions that require a doctor’s care and consultation.”

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Krissy Brady Krissy is a regular contributor to Prevention, and she also writes for Cosmopolitan, Weight Watchers, Women’s Health, FitnessMagazine.com, Self.com, and Shape.com.

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