Why does my poop smells like chemicals?

Reviewed by Yoshinori Abe, MD

Internal Medicine

Poop can smell like chemicals due to several factors, including diet, medications, gut bacteria imbalances, or underlying digestive conditions. Common causes include high-protein or high-fat foods, alcohol, antibiotics, lactose intolerance, infections like C. difficile, or malabsorption disorders such as celiac disease, Crohn's disease, or pancreatic insufficiency.

Because chemical-smelling stool can signal anything from a minor dietary issue to a more serious gastrointestinal condition, identifying the cause early matters. A free, instant, online symptom check can help you pinpoint likely causes based on your specific symptoms, guide your next steps, and let you know whether home care is enough or if it's time to see a doctor—all in just a few minutes.

Reviewed for medical accuracy: 07/15/2026

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Explanation

When you eat, tiny bacteria in your gut help breakdown food and produce chemicals as a byproduct. These chemicals give your poop its normal smell.

Sometimes, if your food is not digested normally due to an imbalance of harmful versus beneficial gut bacteria or if you have a condition like inflammatory bowel disease, the types or amounts of these chemicals can change. This change can make your poop smell different, like it has a chemical odor.

Foods you eat, or even certain medicines, can also affect the chemicals your body makes in the gut causing a strong or unusual smell.

If you notice a change in smell along with other symptoms like abdominal pain or diarrhea, check your symptoms to help identify potential causes and understand when to seek medical care.

(References)

Chan DK, Leggett CL, Wang KK. Diagnosing gastrointestinal illnesses using fecal headspace volatile organic compounds. World J Gastroenterol. 2016 Jan 28;22(4):1639-49. doi: 10.3748/wjg.v22.i4.1639. PMID: 26819529; PMCID: PMC4721995.
Pueschel L, Nothacker S, Kuhn L, Wedemeyer H, Lenzen H, Wiestler M. Exploring Dietary- and Disease-Related Influences on Flatulence and Fecal Odor Perception in Inflammatory Bowel Disease. J Clin Med. 2024 Dec 29;14(1):137. doi: 10.3390/jcm14010137. PMID: 39797221; PMCID: PMC11720819.

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