Poop Smelling Sweet Lately? This Type of Infection Could Be To Blame (and 7 Other Possible Causes)

"Poop is never going to smell amazing, but yours should smell familiar to you," says Supriya Rao, MD, a gastroenterologist at Tufts Medical Center in Boston, Massachusetts. If you notice your bowel movements have a weirdly sweet odor to them, or you're sensing some kind of other unusual smell, that's usually a sign something is going on with your gastrointestinal (GI) tract.

Here are some potential reasons your poop's been smelling sweet lately, plus ways to prevent abnormal stool odor, and when to see your doctor about it.

Why you have sweet-smelling poop

Poop that smells unusually sweet is often caused by C. difficile (aka, C. diff)—a GI infection that can sometimes develop after taking antibiotics, Dr. Rao says. The odor comes from heightened levels of bile acids in your stool.

Along with a change in smell, C. diff typically causes severe symptoms like watery diarrhea, stomach pain or tenderness, loss of appetite, nausea, and fever, per the Centers for Disease Control and Prevention (CDC). "It's usually very loose diarrhea that's happening multiple times a day," says Dr. Rao.

Heavy diarrhea from C. diff can put you at risk for dehydration, and in severe cases, it can morph into a life-threatening infection. If you think you have it, it's important to seek treatment. Your care team will prescribe specific antibiotics to fight off the C. diff bacteria.

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Other reasons why your poop might smell different

While C. diff is the main cause of sweet-smelling poop, other things can also affect stool odor, Dr. Rao notes. That can include:

Alcohol

Heavy drinking can cause changes to the bacteria in your microbiome, killing off some of the friendly bugs and making it easier for harmful ones to thrive. That could make your poop smell different, though there's no one particular smell that's associated with booze, Dr. Rao notes.

Certain foods

Red meat, in particular, can throw off your poop smell because it produces sulfur-containing compounds as it's digested, per the National Library of Medicine (NLM). You might not notice anything unusual if you eat meat regularly, because it's just part of your normal poop smell. But you might notice your poop has a stronger odor after eating meat if you don't usually eat it, Dr. Rao points out.

Antibiotics

Antibiotics work by wiping out both the bad and good bacteria in your gut, which can lead to changes in the microbial communities that live there. That can, in turn, change up the amount and type of bacteria that end up in your poop, which might make it smell stinkier than usual, suggests an older June 2004 study in Applied and Environmental Microbiology¹. Another February 2022 study in Microbiology Open² found that certain antibiotics (like clindamycin) may even promote the colonization of potential pathogens like C. diff, which can lead to diarrhea, and therefore, sweet-smelling poop.

Malabsorptive conditions

Any condition where a person's GI tract is unable to properly absorb a certain type of food can potentially cause poop changes if that food gets eaten. Two of the most common? Lactose intolerance and celiac disease. If a lactose intolerant person eats dairy or a person with celiac eats gluten, "that would cause stool to be more foul-smelling," Dr. Rao says. Again, it all comes down to changes that occur in the microbiome that stem from eating a food that your GI tract doesn't like, suggests a January 2016 study in the World Journal of Gastroenterology³.

Irritable bowel syndrome (IBS)

IBS—an intestinal disorder that causes abdominal pain, bloating, and diarrhea or constipation—might give your poop a foul or slightly alcoholic smell. That could be due to high numbers of bad bacteria in the gut, which can also end up in poop and change the odor, the World Journal of Gastroenterology study noted.

Inflammatory bowel disease (IBD)

Inflammatory bowel diseases like Crohn's disease or ulcerative colitis can have a similar effect on gut bacteria and change a person's stool odor, the World Journal of Gastroenterology study added. Other factors could also come into play: "If it smells a little metallic-y, there could potentially be some blood in your stool," which can stem from Crohn's or ulcerative colitis inflammation, Dr. Rao points out.

Liver disease

Poop that has an ammonia-like smell could be a sign of liver disease, says Dr. Rao. Ammonia is a normal byproduct of protein digestion, and a healthy liver is responsible for clearing the ammonia out. But if your liver isn't functioning the way that it should, some of that ammonia could end up in your stool instead. Other signs of liver problems can include yellowing of the skin or eyes, abdominal pain or swelling, leg or ankle swelling, itchy skin, dark urine, or poop that looks paler than usual, per the Mayo Clinic.

Could it be a sign of cancer?

In rare cases, foul-smelling stools that are loose, watery, or oily could be a sign of pancreatic cancer. When the pancreas isn't functioning the way it should, nutrients aren't absorbed properly, which can lead to changes in your poop, according to New York-Presbyterian Columbia University Irving Medical Center.

Pancreatic cancer is uncommon, but it can cause other symptoms like yellow skin or eyes, abdominal pain, and unintentional weight loss. It's best to see your doctor if you have these symptoms; they can run tests to rule out any underlying conditions, including cancer.

How to treat sweet-smelling poop

Addressing any changes in your stool odor starts with pinpointing what's driving the change, Dr. Rao notes. Some problems, like poop changes from antibiotics, will usually clear up on their own, but eating foods rich in probiotics and prebiotics can help the bugs in your gut get back to baseline faster, she adds.

If you think the smell is being driven by an underlying health condition, it's best to see your doctor, especially if your poop smells unusually sweet. This could be a sign of a serious infection like C. diff, which requires antibiotic treatment, and in some cases, hospitalization to prevent dehydration and other complications.

How to prevent changes in your poop

You can't always avoid poop changes, especially if you have to take antibiotics or you develop an infection. But certain lifestyle habits can support your overall health, which in turn can support the health of your gut, Dr. Rao says. TBH, it's all about sticking with basics like the following, she adds:

• Diet: Eating a wholesome, high-fiber diet rich in fruits, vegetables, whole grains, nuts, seeds, and healthy fats.
• Exercise: Trying to be active every day. Getting at least 30 minutes of exercise five days a week should help with digestion and overall health, per the Cleveland Clinic.
• Sleep: Getting the recommended 7 to 8 hours of sleep, per the CDC.
• Stress reduction: Finding ways to stay on top of your stress, which can help reduce GI symptoms that come with things like IBS, per Harvard Health Publishing.

When to see a doctor

Let your doctor know of any new or unusual changes in bowel habits that last for more than a few days, or about persistent abdominal pain, bloating, gas, diarrhea, or constipation. These symptoms can have a ton of different possible causes, and your doc can help you get to the bottom of what's going on.

And seek immediate medical attention for signs of a possible C. diff infection, like severe diarrhea, abdominal swelling, or fever.

FAQ

What does melena (i.e., black stool) smell like?

"Melena" is medical speak for stool that's black and tarry due to bleeding in the upper GI tract, per the Cleveland Clinic. It has a foul-smelling odor that some people compare to rotten eggs or nail polish remover. It can have a wide range of causes, most of which are serious: Think bleeding ulcers, tears in the lining of your stomach or esophagus, ruptured stomach veins, certain cancers, or even the ebola virus, per the Cleveland Clinic. If you think you have melena, call your doctor and go to the nearest emergency room to be treated.

Is sweet-smelling poop a sign of diabetes?

Diabetic ketoacidosis, a life-threatening complication that happens when the body begins breaking down fat for energy at a rapid rate, can often make a person's breath or urine smell sweet or fruity. But it's doesn't typically affect the smell of your poop, according to the NLM.

The condition, which is more likely to affect people with type 1 diabetes than those with type 2, can also cause the following symptoms, per the NLM:

• Rapid breathing
• Dehydration
• Dry mouth
• Facial flushing
• Headache
• Muscle stiffness
• Nausea or vomiting

Diabetic ketoacidosis is a medical emergency and can be life-threatening. If you have diabetes and feel these symptoms, call 911 or go to the nearest emergency room.

Does lactose intolerance cause sweet-smelling poop?

Not usually, says Dr. Rao. But if you eat dairy when you're lactose intolerant, you'll probably get foul-smelling diarrhea along with gas, bloating, and abdominal pain within two hours of having the offending food or drink, per the Mayo Clinic.

—reviewed by Jennifer Logan, MD, MPH