Green urine is almost always caused by something you ate, drank, or took as medication. It looks alarming, but in most cases the color change is harmless and clears up on its own within a day or two. Less commonly, green urine can signal a bacterial infection or a problem with bile flow from the liver.
Medications That Turn Urine Green
Medications are the single most common reason urine turns green. Several widely used drugs can do this, and the color change is a known, expected side effect rather than a sign of harm. The list includes indomethacin (a pain and arthritis drug), amitriptyline (an antidepressant), promethazine (used for nausea and allergies), cimetidine (a heartburn medication), and triamterene (a water pill), all of which can shift urine toward green or blue-green.
Propofol, the anesthetic used before surgery, is another well-documented cause. If you notice green urine after a procedure, propofol is the likely explanation. In reported cases, the color returned to normal anywhere from two hours to two days after the drug was stopped, with most people seeing it resolve within about 12 hours. Methylene blue, sometimes used as a diagnostic dye or treatment for certain conditions, can also produce vivid blue-green urine.
If you recently started a new medication and your urine changed color, check the drug’s side effect profile or ask your pharmacist. No treatment is needed for the color change itself.
Foods and Dyes
Asparagus can give urine a greenish tint along with its famously strong smell. The green comes from plant pigments that pass through your kidneys largely intact. Artificially colored foods and drinks are another frequent culprit. Blue food dyes, particularly FD&C Blue No. 1, mix with the natural yellow of urine to produce green. Think brightly colored sports drinks, candy, ice cream, or frosting. The more concentrated the dye and the less water you’ve been drinking, the more vivid the result.
Food-related green urine typically resolves within one to two urinations once you stop consuming the offending item and drink some extra water.
Bacterial Urinary Tract Infections
A specific type of bacteria called Pseudomonas aeruginosa can produce green urine through a pigment it manufactures called pyocyanin. This isn’t a typical UTI caused by E. coli. Pseudomonas infections are more common in people with catheters, weakened immune systems, or recent hospital stays.
The key difference from a harmless cause is that a Pseudomonas UTI comes with other symptoms: burning during urination, frequent urges to go, cloudy or foul-smelling urine, pelvic pain, or fever. Green urine paired with any of these warrants a urine culture so the right antibiotic can be chosen. Pseudomonas doesn’t respond to many standard UTI treatments, so accurate identification matters.
Bile and Liver Problems
Your liver constantly processes old red blood cells, producing a green pigment called biliverdin as an intermediate step before converting it to the yellow-orange bilirubin you may have heard of. Normally biliverdin doesn’t accumulate in noticeable amounts. But when bile flow is blocked, a condition called cholestasis, or when the liver is failing, biliverdin can build up in the blood and spill into urine, turning it green.
This is a less common cause, but it’s the one that signals a serious underlying problem. Bile obstruction from gallstones, tumors, or liver disease typically comes with other obvious signs: yellowing of the skin or eyes, pale or clay-colored stools, dark urine that shifts toward green, itching, nausea, or upper abdominal pain. If green urine appears alongside any of these symptoms, it points to a biliary or liver issue that needs prompt evaluation.
Rare Genetic Conditions
A handful of inherited metabolic disorders can cause blue or green urine, though these are almost exclusively diagnosed in infancy. Blue diaper syndrome, for example, results from a defect in how the intestines absorb the amino acid tryptophan. Gut bacteria break the excess tryptophan down into a compound called indican, which converts to indigo blue dye when exposed to air. Parents typically notice distinctive blue-green stains on their baby’s diapers.
Hartnup disease, another rare disorder affecting amino acid absorption, can also shift urine toward blue. Alkaptonuria, which disrupts the breakdown of certain amino acids, can produce dark blue urine. These conditions are rare enough that they’re almost never the explanation for an adult noticing green urine for the first time.
How to Figure Out Your Cause
Start with the simplest explanation. Think back over the last 24 to 48 hours: did you eat anything with bright blue or green coloring? Start a new medication or supplement? Have a medical procedure involving anesthesia? If the answer to any of these is yes, that’s your most likely cause. Drink extra water and see if the color fades with your next few bathroom trips.
If you can’t identify an obvious trigger, or if the green color persists for more than two days, a basic urine test (dipstick urinalysis) can check for signs of infection, blood, or excess bilirubin. For suspected infections, a urine culture can identify the specific bacteria involved. More specialized testing exists for metabolic causes, but doctors typically reserve those for cases where the history, symptoms, and basic labs don’t explain the color change.
Green urine with no other symptoms and a clear dietary or medication explanation is almost never a problem. Green urine accompanied by fever, pain, jaundice, or changes in stool color is a different situation and worth getting checked promptly.