Lime green poop usually means food moved through your digestive system faster than normal, or you recently ate something with a lot of green pigment. In most cases, it’s harmless and resolves on its own within a day or two. Less commonly, it can signal an infection or a digestive condition worth paying attention to.
The color comes down to bile, a yellow-green fluid your liver produces to help digest fats. As bile travels through your intestines, bacteria chemically break it down, gradually shifting its color from green to yellow to brown. When something disrupts that process, stool keeps more of its original green tint.
How Bile Creates Green Stool
Your liver constantly produces bile and stores it in the gallbladder. After you eat, bile gets released into the small intestine to help break down fats. As it continues through the large intestine, bacteria act on the bile salts and change their pigment from green to brown. That’s why healthy stool is typically some shade of brown.
When stool moves through the large intestine too quickly, bile doesn’t have enough time to complete that color change. The result is stool that looks green, sometimes a vivid lime green. This is the single most common explanation, and it often accompanies diarrhea from any cause. A stomach bug, food that didn’t agree with you, too much coffee, stress: anything that speeds up your gut can produce green stool simply because bile stayed green.
Foods and Drinks That Turn Stool Green
Chlorophyll, the pigment that makes plants green, can do the same to your stool. Spinach, kale, broccoli, avocados, pistachios, fresh herbs, and matcha (powdered green tea) are all common culprits. You don’t need to eat an unusual amount. A large salad or a green smoothie is often enough, especially if you don’t regularly eat that many greens.
Artificial food coloring is another frequent cause. Brightly frosted cupcakes, candy, sports drinks, and ice cream with blue or green dyes continue tinting whatever they touch as they pass through your digestive tract. Blue dye mixed with yellow bile can produce a particularly striking lime green. If your stool turned green within 12 to 24 hours of eating something colorful, that’s almost certainly the explanation.
Infections That Cause Green Diarrhea
Bacterial infections like Salmonella and E. coli, viral infections like norovirus, and parasites like Giardia can all cause green stool. These pathogens irritate the intestinal lining and trigger a rapid “gush” of unabsorbed bile through the digestive tract. The stool comes out green because transit time drops dramatically during active infection.
The distinguishing factor here is context. Infection-related green stool almost always comes with other symptoms: watery diarrhea, cramping, nausea, fever, or vomiting. If you ate something questionable, traveled recently, or drank untreated water and then developed green diarrhea with these symptoms, an infection is a likely explanation. Most cases resolve on their own, but staying hydrated is critical since the biggest risk from these infections is dehydration, not the green color itself.
Medications and Supplements
Some antibiotics can tint stool yellow or green by disrupting the gut bacteria that normally convert bile from green to brown. Without enough of those bacteria doing their job, bile passes through with more of its original pigment intact. This is temporary and typically resolves once you finish the antibiotic course and your gut bacteria repopulate.
Iron supplements are another common cause. They usually turn stool dark green or black rather than lime green, but the shade varies depending on the formulation and how much iron your body absorbs. If you recently started an iron supplement and noticed a color change, that’s a normal and expected side effect.
Green Stool in Babies
Green poop in infants is common and rarely a concern. Breastfed babies may produce green stool if they don’t finish feeding on one side before switching. The earlier milk (foremilk) is thinner and lower in fat, while the later milk (hindmilk) is richer. When a baby gets mostly foremilk, digestion speeds up and stool can turn green. Letting your baby finish one breast before offering the other often resolves this.
Formula-fed babies on protein hydrolysate formulas, which are used for milk or soy allergies, frequently have green stool. This is a known effect of the formula composition and not a sign of a problem. Newborns who are exclusively breastfed may also have green stool simply because their gut bacteria haven’t fully established yet. And of course, diarrhea from any cause in infants can produce green stool for the same bile-transit reasons it does in adults.
Liver and Gallbladder Conditions
Conditions that affect the liver or gallbladder can cause chronically green stool by altering how much bile enters the intestine or how it gets processed. When the gallbladder releases excess bile, or when the liver produces bile in unusual quantities, more green pigment makes it into your stool than bacteria can convert to brown. This is less common than dietary or transit-related causes, but it’s worth considering if green stool persists for more than a few days without an obvious dietary explanation.
When Green Stool Needs Attention
A single episode of lime green poop, or even a few days of it after a dietary change, is not a concern. The color alone tells you very little about your health. What matters is the pattern and what accompanies it.
Green stool that persists for more than a few days without a clear dietary cause is worth mentioning to a healthcare provider. The same goes for green stool accompanied by fever, blood or mucus, severe cramping, or signs of dehydration like dark urine, dizziness, or dry mouth. In children and infants, dehydration can develop quickly during diarrhea episodes, so keeping fluid intake up is especially important. For most people, though, lime green poop is a temporary curiosity with a simple explanation: something you ate, or a gut that was moving a little faster than usual.