Green-tinted urine is almost always caused by something you ate, drank, or took as a supplement or medication. It looks alarming, but in most cases it’s harmless and clears up within a day. Less commonly, green urine can signal a urinary tract infection or a problem with the liver or bile ducts.
Foods and Dyes That Turn Urine Green
Asparagus is the most well-known culprit. It can give urine a greenish hue along with a distinctive sulfurous smell often compared to rotting cabbage. Artificially colored foods and drinks are another common cause, particularly anything containing blue or green food dyes. Blue dye mixed with the natural yellow of urine produces a green color, which is why brightly colored sports drinks, candy, ice cream, or frosting can have this effect.
If food or dye is the cause, the color change typically appears within a few hours of eating and clears within 24 hours as your body finishes processing and excreting the pigment.
B Vitamins and Supplements
B vitamins are water-soluble, meaning your kidneys flush out whatever your body doesn’t need. Riboflavin (B2) makes urine bright yellow, and when that intense yellow mixes with other pigments from B-complex supplements or multivitamins, the result can look fluorescent yellow-green. This is especially common after taking a high-dose B-complex supplement or a multivitamin with large amounts of B vitamins.
The neon tint is simply your body discarding the excess. It’s not a sign of harm, and it fades once the vitamins have been fully excreted, usually within several hours.
Medications That Cause Green Urine
Several prescription and over-the-counter medications can turn urine green. The mechanism varies by drug. Some contain compounds called phenols, which get processed in the liver and produce green-tinted byproducts that end up in the urine. Medications in this category include promethazine (an anti-nausea drug), cimetidine (used for acid reflux), and propofol (an anesthetic used in hospital settings).
Other medications cause green urine through different chemical pathways. These include amitriptyline (a tricyclic antidepressant), indomethacin (a nonsteroidal anti-inflammatory), and metoclopramide (used for nausea and gastroparesis). Methylene blue, a medical dye sometimes included in certain bladder medications, is another well-documented cause. It peaks in urine about two to six hours after ingestion and remains detectable for roughly 24 hours.
If you recently started a new medication and notice green urine, the drug is very likely the explanation. The color change is a cosmetic side effect, not a sign that the medication is causing damage.
Urinary Tract Infections
Certain bacteria produce green pigments as part of their metabolism. A urinary tract infection caused by one of these bacteria, most notably Pseudomonas species, can give urine a greenish color. Unlike the dietary or medication causes above, a bacterial infection will usually come with other symptoms: burning or pain during urination, frequent urges to urinate, cloudy or foul-smelling urine, or pelvic discomfort. Green urine from a UTI won’t resolve on its own and needs antibiotic treatment.
In rare cases, bacteria that produce green pigments can also enter the bloodstream, a condition called bacteremia. This is more of a concern in hospitalized patients or people with weakened immune systems than in otherwise healthy adults.
Liver and Bile Duct Problems
Your liver produces a green pigment called biliverdin as part of the normal breakdown of red blood cells. Biliverdin is usually converted into bilirubin (a yellow pigment) and excreted through bile. When the bile ducts are blocked or the liver isn’t functioning properly, biliverdin can accumulate and spill into the urine, turning it green.
Conditions that can cause this include gallstones blocking a bile duct, liver failure, and rarely, congenital abnormalities of the bile ducts. Green urine from a biliary or liver problem is typically accompanied by other noticeable symptoms: yellowing of the skin or eyes, pale-colored stools, dark urine that shifts between brown and green, abdominal pain (particularly in the upper right side), or general fatigue. If green urine appears alongside any of these symptoms, it points to something that needs prompt medical evaluation.
Rare Metabolic Conditions
A handful of inherited metabolic disorders can produce blue or green urine from birth. Blue diaper syndrome, for example, is a rare condition where the body can’t properly absorb the amino acid tryptophan. Bacteria in the gut break down the excess tryptophan into a compound called indican, which converts to an indigo blue dye when exposed to air. Parents typically notice blue-green stains on their infant’s diaper. These conditions are diagnosed in infancy and are extremely uncommon, so they’re not a likely explanation for an adult noticing green urine for the first time.
How to Figure Out the Cause
Start by thinking about the last 24 hours. Did you eat anything with blue or green food coloring? Take a B-complex vitamin or multivitamin? Eat asparagus? Start a new medication? If the answer to any of these is yes, that’s almost certainly your explanation, and the color should return to normal within a day once you stop consuming the trigger.
If green urine persists for more than two days with no dietary or medication explanation, or if it comes with pain, burning, fever, or any of the liver-related symptoms described above, it’s worth getting a urinalysis. A simple urine test can quickly distinguish between a bacterial infection and a benign cause, and blood work can check liver function if there’s any concern about bile flow.