A shart is when you try to pass gas and accidentally release some stool along with it. The word is a blend of the two acts involved. It’s extremely common, rarely a sign of anything serious, and happens because your body’s system for telling gas apart from stool isn’t perfect.
How Your Body Tells Gas From Stool
Your rectum has a built-in sampling system. When gas or stool moves into the lower rectum, a reflex causes the inner ring of muscle at the opening of your anus to briefly relax. This lets a tiny amount of rectal contents contact the nerve-rich lining of the upper anal canal, which sends a signal to your brain: gas, liquid, or solid. Your brain then decides whether it’s safe to let it pass.
This system works well most of the time, but it has limitations. When stool is loose or watery, the nerves have a harder time distinguishing it from gas. The liquid moves fast, fills the rectum quickly, and can slip past before the outer sphincter (the one you control voluntarily) has time to clamp down. That’s the basic mechanics of a shart: your body misidentifies liquid stool as gas, relaxes the inner sphincter, and by the time you realize the mistake, some has already escaped.
Why It Happens
The single biggest risk factor is loose stool. Anything that makes your stool more liquid makes a shart more likely, because watery stool is harder to hold in and easier to mistake for gas. Common triggers include:
- Caffeine and alcohol. Both speed up gut motility and can loosen stool.
- Sugar alcohols. Sweeteners like sorbitol, maltitol, and lactitol (found in sugar-free gum, candy, protein bars, and some “keto” snacks) pull water into the intestine. This creates loose, gassy stool, which is basically the perfect recipe for a shart. Sorbitol and maltitol are the worst offenders. Erythritol, a smaller molecule, tends to cause far fewer problems.
- Dairy products. If you’re even mildly lactose intolerant, undigested lactose draws water into the gut the same way sugar alcohols do.
- Fatty or greasy foods. High-fat meals can trigger faster movement through the colon.
- Illness. A stomach bug, food poisoning, or any infection causing diarrhea makes accidental leakage far more likely for the duration of the illness.
Conditions like irritable bowel syndrome and inflammatory bowel disease also increase the odds, because they cause unpredictable shifts between loose and normal stool.
How Common It Actually Is
More common than most people think. National health survey data from the U.S. found that about 8.3% of adults experienced at least one episode of accidental bowel leakage in the previous month. That’s roughly 1 in 12 people. The rates were nearly identical for men (7.7%) and women (8.9%). About 2.7% of adults reported it happening at least once a week.
Those numbers cover the full spectrum of accidental leakage, from a minor shart to more significant episodes. But the point stands: it’s not rare, and it’s not something only elderly or unhealthy people deal with.
Reducing the Odds
Since loose stool is the main culprit, the most effective strategy is managing what makes your stool loose in the first place. If sugar-free products are a regular part of your diet, check the label for sorbitol, maltitol, or lactitol and consider cutting back. If you notice it tends to happen after coffee on an empty stomach, or after a heavy meal, those are patterns worth adjusting.
Increasing fiber intake helps many people by adding bulk to stool, making it more solid and easier for the rectum to identify correctly. Soluble fiber (found in oats, bananas, and psyllium) is particularly useful because it absorbs water and firms things up.
Pelvic floor exercises also make a measurable difference. The external anal sphincter is a skeletal muscle you can strengthen, just like any other. The technique is the same as a Kegel: contract the muscles you’d use to stop the flow of urine or hold in gas, hold for a few seconds, then release. Practicing both sustained holds and quick contractions builds the strength and reaction time that help you catch a shart before it happens. One common training method compares the pelvic floor to an elevator, practicing contractions at different intensities as if stopping at different floors.
Timing matters too. If you know certain meals tend to trigger loose stool, planning your bathroom visits around those meals (going before you leave the house, for instance) reduces the chance of being caught off guard.
When It’s More Than a One-Off
A single shart after a greasy meal or a stomach bug is normal and not worth worrying about. But if it’s happening regularly, especially weekly or more, that pattern has a name in medicine: fecal incontinence, sometimes called accidental bowel leakage. It can signal weakened pelvic floor muscles, nerve damage (sometimes from childbirth, surgery, or conditions like diabetes), chronic diarrhea from an undiagnosed food intolerance, or an inflammatory condition affecting the bowel. Persistent diarrhea or constipation are the most common underlying causes, and both are treatable once identified.