Green urine almost always results from something you swallowed, were injected with, or, less commonly, an infection producing pigmented byproducts. The underlying optics are straightforward: normal urine is yellow because of a pigment called urochrome, and when a blue or green compound enters the urinary tract, it blends with that yellow baseline to produce shades ranging from lime to dark emerald. The causes span everyday foods and supplements all the way to serious infections and liver dysfunction, so whether green pee is trivial or worth a phone call to your doctor depends entirely on context.
Why Urine Turns Green in the First Place
A 1974 overview in JAMA put it simply: green urine is a mixture of blue and yellow. The yellow comes from urochrome, a breakdown product of hemoglobin that your kidneys filter into urine every day. When a blue-tinged substance enters the mix, the result looks green to the eye, the same way mixing blue and yellow paint gives you green. If the added pigment is already green on its own, the effect is even more obvious. This basic color-mixing principle explains why so many unrelated substances, from medications to food dyes to bacterial pigments, can all produce the same alarming hue in the toilet bowl.1JAMA. Urine in Technicolor
Medications That Can Turn Your Urine Green
Drugs are the single most common cause of green urine in a clinical setting, and the list is longer than most people expect. Several of these medications contain phenolic ring structures that the liver converts into green-tinted byproducts, which then pass out through the kidneys. The discoloration is usually dose-related and clears up once the drug is stopped.2PubMed. Differentials of abnormal urine color: A review
Propofol, the intravenous anesthetic widely used for sedation in operating rooms and intensive care units, is probably the best-known green-urine culprit among healthcare workers. When the body clears propofol faster than the liver alone can handle, some of it gets processed by other organs and the resulting metabolites tint the urine green. This happens in fewer than one in a hundred patients, and it is considered a harmless side effect that resolves once the infusion stops.3PubMed Central. Green Urine Due to Propofol: A Case Report with Review of Literature
Methylene blue is another frequent offender. It is used during certain surgical procedures to test for leaks in the bowel, to identify tissue planes, and sometimes to treat a dangerous drop in blood pressure called vasoplegic syndrome. Because methylene blue is literally a vivid blue dye, it mixes with the yellow urochrome to produce strikingly green urine. In one reported case, an 85-year-old man alarmed an entire nursing team when he voided bright green urine after bowel surgery in which methylene blue had been injected into his intestine. His urine cultures and liver tests came back normal, and the color faded on its own within days.4BMJ Case Reports. Green urine in a postoperative patient
Beyond propofol and methylene blue, documented pharmaceutical causes include the antacid cimetidine, the anti-nausea drug metoclopramide, the antihistamine promethazine, the anti-inflammatory indomethacin, the muscle relaxant methocarbamol, and the tricyclic antidepressant amitriptyline.5PubMed. Green Urine And Altered Mental Status: A Case Of Intoxication If you notice green urine and you recently started any medication, a quick scan of the drug’s known side effects or a call to your pharmacist is usually the fastest way to connect the dots.
Food Dyes and Dietary Causes
You do not need to be in a hospital to end up with green urine. Artificial food colorings, particularly blue dyes, are a well-documented cause. FD&C Blue No. 1, used in everything from sports drinks to candy to colored frostings, can be absorbed through the gut in large enough quantities to tint urine green. One case involved a critically ill patient in the ICU whose dark green urine puzzled his medical team until they traced the color to the blue dye added to his tube-feeding formula, a practice that was common at the time to help detect aspiration. Spectrophotometric analysis of his urine confirmed the dye was the culprit.6American Journal of Kidney Diseases. Green urine in a critically ill patient
That hospital practice of dyeing tube feeds blue has since fallen out of favor, partly because the dye complicated urine and stool assessment and partly because absorption of the dye was linked to adverse outcomes in vulnerable patients.7PubMed. Food dye use in enteral feedings: a review and a call for a moratorium For healthy people who are not tube-fed, the occasional green tinge after consuming heavily dyed foods or drinks is harmless and short-lived. Asparagus is sometimes blamed for greenish urine as well, though it more reliably produces a strong odor than a color shift. Consuming large quantities of green-colored supplements, particularly those containing chlorophyll or spirulina, can also push urine toward green.
Infections, Especially Pseudomonas
Among infectious causes, the bacterium Pseudomonas aeruginosa stands out. This organism produces blue-green pigments called pyocyanin and pyoverdine as part of its normal metabolism. When Pseudomonas infects the urinary tract, those pigments dissolve into the urine and combine with the usual yellow urochrome to produce distinctly green urine. The connection was recognized decades ago; the 1974 JAMA overview specifically noted that Pseudomonas infection, with its blue pus, combines with urochrome to emerge as green.8JAMA. Urine in Technicolor Case reports continue to appear in the emergency medicine literature confirming the association.9PubMed. Green urine due to Pseudomonas urinary tract infection: An unusual occurence
Pseudomonas urinary tract infections are uncommon in otherwise healthy people. They tend to show up in patients with urinary catheters, weakened immune systems, or prolonged hospital stays. If green urine is accompanied by fever, pain during urination, or a foul smell, an infection is worth ruling out promptly, because Pseudomonas can be resistant to many standard antibiotics and may need targeted treatment.
Liver Problems and Biliverdin
The liver plays a central role in breaking down old red blood cells. Hemoglobin from those cells is first converted to biliverdin, which is green, and then quickly converted again to bilirubin, which is yellow-orange. Under normal circumstances, biliverdin exists only briefly before the enzyme biliverdin reductase transforms it. But when liver function is compromised, or when that enzyme does not work properly, biliverdin accumulates and can spill into the urine.
A striking example was described in a patient with liver cirrhosis who also carried a rare mutation in the gene for biliverdin reductase. The patient’s skin, the whites of the eyes, plasma, urine, and even abdominal fluid all had a greenish appearance. Bilirubin levels were normal, and there was no sign of red blood cell destruction; the green color was entirely due to elevated biliverdin.10PubMed. A novel mutation in the biliverdin reductase-A gene combined with liver cirrhosis results in hyperbiliverdinaemia (green jaundice) This condition, sometimes called green jaundice, is extremely rare, but it illustrates how a breakdown in a single metabolic step can dramatically change urine color.
In patients with heart failure, the interplay between liver and kidney can also produce green urine when methylene blue is used therapeutically. Reduced blood flow to both organs slows the clearance of methylene blue and its metabolites, allowing the pigment to linger and discolor the urine for longer than it otherwise would.11PubMed Central. An interesting observation: prolonged green urine can be a combined effect of decreased liver and renal function in a patient with heart failure—a case report In those cases, the green urine is not itself dangerous, but it can signal that drug clearance is impaired, which matters for dosing decisions.
Surgical Procedures and Postoperative Surprises
Green urine after surgery catches patients and staff off guard with some regularity. Diagnostic dyes like indigo carmine and methylene blue are injected during various procedures to check for leaks, map anatomical structures, or assess blood flow. These dyes are cleared through the kidneys, and their vivid color survives the trip. The discoloration typically appears within hours of surgery and resolves on its own within a day or two.12PubMed Central. Greenish discoloration of urine in a postoperative patient
A more unusual postoperative scenario was reported after a biliary drainage procedure. A patient who had undergone a procedure to reroute bile flow developed dark green urine appearing each afternoon. The medical team suspected an abnormal connection had formed between the biliary system and a blood vessel, allowing bile pigments to enter the bloodstream and eventually reach the kidneys.13PubMed Central. Dark green urine following endoscopic ultrasound-guided hepaticogastrostomy: A case report That case was unusual enough to merit a published report, but it underscores that green urine after a biliary or abdominal procedure warrants a conversation with the surgical team rather than a shrug.
How Green Urine Can Fool a Dipstick Test
Here is a wrinkle that matters if you are a patient whose urine is being tested in a lab. Standard urine dipsticks, the paper strips dipped into a sample to check for protein, blood, glucose, and other markers, rely on color-change chemistry. A strongly pigmented urine sample can interfere with those color readings. In one documented case, methylene blue in the urine caused a dipstick to read 3+ for albumin, which would normally suggest serious kidney disease. But when the same urine was tested with a more precise laboratory method, the actual protein concentration was only 18 milligrams per deciliter, which is essentially normal. The blue pigment had fooled the dipstick’s color pad.14PubMed. Blue-green discoloration of urine and false nephrotic range proteinuria at dipstick urinalysis
This kind of interference is worth knowing about because a false-positive protein reading could trigger unnecessary follow-up tests, worry, or even treatment if the clinician does not realize the urine is discolored. If your urine is visibly green or blue at the time of a dipstick test, make sure whoever reads the results knows about the color so they can send the sample for confirmatory testing using a method that is not thrown off by pigments.
When to Worry and When to Relax
Most episodes of green urine are benign and self-limiting. If you can trace the color to a food, a supplement, or a medication you are taking, and you feel fine otherwise, the urine will almost certainly return to normal once the substance clears your system. Staying well hydrated tends to speed that along by diluting the pigment.
Green urine deserves medical attention when any of the following apply:
- Accompanying symptoms: Fever, pain while urinating, flank pain, or foul-smelling urine suggest a possible urinary tract infection, including one caused by Pseudomonas.
- No obvious dietary or drug cause: If you have not eaten anything unusually colored, are not on any relevant medications, and have not had a recent procedure, the color may point to a metabolic or hepatic issue worth investigating.
- Prolonged duration: A day or two of green urine after eating blue-frosted cake is one thing. Persistent green urine lasting a week or more without explanation warrants bloodwork and a urine culture.
- Known liver or kidney disease: In people with existing organ impairment, green urine can signal that drug clearance is slowed, which has implications for medication dosing and monitoring.
A clinical case report published in Cureus in 2025 emphasized that blue-green urine remains rare and under-studied compared with red or brown discoloration, and that a careful review of a patient’s medication list and recent history is usually the most efficient path to a diagnosis.15PubMed Central. Diagnostic Approach to Abnormal Urine Colors: Lessons From a Case of Blue-Green Urine
Green Urine in Dogs and What It Reveals About Genetics
Humans are not the only species that can produce green urine. In 2024, researchers described two dogs with persistent green urine caused by an inherited defect in the same enzyme, biliverdin reductase, that was implicated in the human green-jaundice case discussed earlier. Whole-genome sequencing revealed that each dog carried large deletions in the gene BLVRA, knocking out the enzyme’s ability to convert biliverdin to bilirubin. As a result, biliverdin accumulated and poured into the urine. One dog had urinary biliverdin levels 43 times higher than normal, and the other had levels 10 times higher.16PubMed Central. Biliverdinuria Caused by Exonic BLVRA Deletions in Two Dogs with Green Urine
These canine cases are interesting beyond veterinary medicine because they demonstrate what happens when a single metabolic step is completely disabled. In humans, the equivalent enzyme deficiency is vanishingly rare and seems to require a combination of the genetic mutation and existing liver disease to produce visible symptoms. In the dogs, the genetic defect alone was enough. That difference may reflect how much backup metabolic capacity the human liver has under normal conditions, a capacity that cirrhosis or heart failure can erode.
Common Myths and Misunderstandings
One persistent myth is that green urine automatically means you have a serious infection. While Pseudomonas can cause it, infections are actually one of the less common reasons. Medications, dyes, and foods account for the vast majority of cases. Another misconception is that green urine signals liver failure. Biliverdin-related green urine from liver dysfunction is genuinely rare; most people with liver disease develop the classic yellow-orange jaundice from bilirubin, not green jaundice from biliverdin.
A subtler misunderstanding involves the idea that urine color alone can serve as a reliable diagnostic tool. Urine color gives your doctor a clue, not a diagnosis. The same green shade could come from propofol, a Pseudomonas infection, blue Gatorade, or a genetic enzyme deficiency. Without knowing what you recently ate, drank, or were given intravenously, the color by itself narrows the possibilities only a little. That is why every published case report on the topic circles back to the same practical advice: take a thorough medication and dietary history before ordering expensive tests.
Finally, people sometimes worry that green urine means the kidneys themselves are damaged. In nearly all documented cases, the kidneys are functioning normally and are simply doing their job of filtering pigmented compounds out of the blood. The one exception to keep in mind involves high-dose methylene blue in patients with impaired organ function, where the prolonged green discoloration reflects slowed clearance rather than direct kidney injury.17PubMed Central. An interesting observation: prolonged green urine can be a combined effect of decreased liver and renal function in a patient with heart failure—a case report Even then, the green color is a marker of the underlying organ dysfunction, not a sign that the dye is harming the kidneys.