Lime green urine is almost always caused by something you ate, drank, or took as a medication or supplement. It looks alarming, but in most cases the color is harmless and temporary. The three most common explanations are artificial food dyes, certain medications, and B vitamins, though in rare cases it can signal a problem with the liver or biliary system.
Food Dyes and Colored Drinks
Artificial dyes are one of the most frequent culprits. Blue and green food colorings, particularly those found in brightly colored sports drinks, candies, popsicles, cake frosting, and certain cereals, pass through your digestive system largely intact. Your kidneys filter them out, and the dye ends up concentrated in your urine. Blue dye mixing with the natural yellow of urine often produces a vivid lime or neon green.
If you recently had anything with a bold artificial color, that’s likely your answer. The green tint typically clears within a day or two once you stop consuming the dyed food or drink, especially if you’re staying well hydrated.
B Vitamins and Supplements
Multivitamins and B-complex supplements are another extremely common cause. Riboflavin (vitamin B2) is water-soluble, meaning your body absorbs what it needs and your kidneys flush the rest into your urine. Riboflavin on its own turns urine a bright, almost fluorescent yellow. But when a supplement also contains blue or green dyes in the tablet coating, those dyes combine with the bright yellow to produce a striking lime green color in the toilet bowl.
This is completely harmless. It simply means your body is excreting excess vitamins it doesn’t need. The effect shows up within a few hours of taking the supplement and fades as your body processes it.
Medications That Turn Urine Green
Several prescription and over-the-counter medications can cause green urine as a known side effect. The most commonly reported ones include:
- Amitriptyline: an antidepressant that can produce greenish-blue urine
- Cimetidine: used for ulcers and acid reflux
- Indomethacin: a pain and arthritis medication
- Triamterene: a diuretic (water pill)
- Promethazine: used for nausea and allergies
- Metoclopramide: a medication for digestive issues
- Propofol: an anesthetic used before surgery
If you recently started a new medication or had a medical procedure, check the side effect information or ask your pharmacist. The color change is a cosmetic effect of how your body metabolizes the drug, not a sign the medication is harming you. Your urine should return to its normal color once you stop taking the medication or your body adjusts.
Bile Pigments and Liver Problems
In rare cases, green urine points to something more significant. Your liver produces a green pigment called biliverdin as part of its normal process of breaking down old red blood cells. Normally, biliverdin gets converted into bilirubin (a yellow pigment) and exits through your stool. But when the bile ducts are blocked or the liver isn’t functioning properly, biliverdin can build up in the blood and spill into the urine, turning it green.
This is associated with conditions like biliary obstruction (a blockage in the tubes that drain bile from the liver), liver failure, and, very rarely, a genetic condition called hyperbiliverdinemia. In these situations, green urine wouldn’t be your only symptom. You’d also typically notice yellowing of the skin or eyes, pale-colored stools, abdominal pain, fatigue, or itching. If you’re experiencing any of those alongside the color change, that warrants prompt medical attention.
Urinary Tract Infections
Certain bacterial infections can also produce green pigments in urine. Pseudomonas is the best-known example, a type of bacteria that produces a blue-green pigment as it grows. A urinary tract infection caused by Pseudomonas can give urine a greenish tint, but you’d almost certainly have other symptoms too: burning or pain when urinating, a frequent urgent need to go, cloudy or foul-smelling urine, or fever.
How to Figure Out Your Cause
Start with the simplest explanation. Think back over the past 24 hours: did you eat or drink anything with bright artificial coloring? Did you take a multivitamin, B-complex supplement, or any new medication? If the answer is yes to any of these, that’s almost certainly the reason, and the color will resolve on its own, usually within one to two days.
If you can’t identify an obvious dietary or medication cause, or if the green color persists for more than two to three days, it’s worth getting a urine test. This is especially true if the color change comes with pain, fever, changes in your stool color, or a yellow tint to your skin. These combinations can point toward infection or a liver or bile duct issue that needs evaluation. On its own, though, a single episode of lime green urine after a neon sports drink or a morning multivitamin is one of those strange but perfectly normal things the body does.