Why do my bowel movements stink so much?

Dear Reader, 

There’s a common saying, “The nose knows.” Particularly foul-smelling bowel movements can sometimes be your body’s way of telling you that something’s up. Based on what you’ve written, it’s hard to tell whether your pungent problem is due to the type of foods that you’re eating or another condition like malabsorption, gastrointestinal issues, or infections (more on these in a bit). However, understanding potential causes can help you decide whether to speak with a health care provider about your concerns and may offer some useful suggestions to keep the funky fumes at bay. 

What you’re smelling might just be the aftermath of a flavorful meal. Foods rich in sulfur can cause your bowel movements to smell more pungent than usual. Foods like herbs and spices (such as garlic, onion, and leek), meat, seafood, dairy products, wine, and things that are fermented can all pack that sulfur punch! Some sulfur compounds are also added to canned and processed foods to limit the growth of harmful microbes. As food moves through your digestive tract, bacteria in your gut break down these sulfur compounds, producing gases as a byproduct. One of these gas byproducts is hydrogen sulfide, known for having an unpleasant, rotten-egg smell. The combination of these gases makes your poop smell, well, like poop. 

Besides the food you eat, certain health conditions and lifestyle factors may also contribute to smelly stools. Some of these include: 

• Steatorrhea: A condition that results in excessive fat in the stool. It can happen if your body is unable to absorb fat properly. Symptoms include greasy, foul-smelling, and light-colored stools that may float on the surface of the water. They may also stick to the side of the toilet bowl and may be difficult to flush away. 
• Malabsorption: This condition affects the body’s ability to absorb certain types of nutrients from food. Symptoms include diarrhea, steatorrhea, abdominal pain, bloating, gas, and nausea. Carbohydrate, fat, and protein malabsorption disorders are associated with foul-smelling and greasy stool. Malabsorption can be caused by inflammatory bowel diseases (such as Crohn’s disease), autoimmune disorders (like celiac disease), and diseases of the pancreas, gallbladder, or liver. 
• Infections: Giardiasis—a diarrheal disease caused by the parasite Giardia duodenalis—can cause foul-smelling diarrhea. Clostridioides difficile, also known as C. diff, is a type of bacteria that can cause inflammation of the large intestine and is associated with diarrhea that has a distinctive, sweet odor. 
• Antibiotics: Diarrhea is a commonly reported side effect of antibiotic treatment. Antibiotics kill off helpful microbes, allowing harmful bacteria to spread in your gut. Changes to the microbiome in your gastrointestinal tract can also affect its ability to break down and absorb certain carbohydrates, leading to diarrhea. 

To pin down the culprit of your noxious number two, it might be helpful to consider the following questions: Are these smelly stools a recent development? Other than smell, do you notice anything different about the color, shape, or consistency of your bowel movements? 

Healthy stool ranges in color from brown to greenish brown. It should have a consistency like toothpaste and leave the body without straining or discomfort. Occasional changes in color and consistency of stool are common and usually caused by what you eat or drink. For instance, eating a lot of green leafy vegetables can cause green-colored stool. That said, it’s recommended that you speak with a health care provider immediately if your stool is bright red, black, pale in color, or accompanied by mucus or pus. Pale stool may be caused by gallstones in the bile ducts or other conditions affecting the liver or pancreas. Red or black stool that isn’t caused by food (think beets, red food coloring, or Oreos) may be a sign of bleeding in the lower or upper gastrointestinal tract. A health care provider may be able to test your breath, stool, or blood to rule out any underlying health conditions such as food intolerances, infections, or nutrient deficiencies. 

In the meantime, if you have access to a window in the bathroom, opening it for ventilation can help to clear the air after your reign on the porcelain throne. Some people enjoy lighting a scented candle to mask unpleasant odors, but this may not be advisable depending on the rules in your residence hall. Perhaps you could bring a decorative touch to the communal bathroom by sprucing up the stalls with potpourri sachets or pre-poop toilet spray? In a pinch, a spritz of air freshener after the fact should also do the trick! 

Smell you later (just kidding)!