Green urine is almost always harmless. In the vast majority of cases, it’s caused by something you ate, drank, or a medication you’re taking, and it resolves on its own. That said, a small number of causes do need medical attention, particularly certain bacterial infections and liver problems. The key is figuring out which category you fall into.
Food Dyes and Supplements
The most common and least concerning cause of green urine is artificial food coloring. Water-soluble dyes found in brightly colored drinks, candies, popsicles, and processed foods can tint your urine green or blue-green as your kidneys filter them out. If you recently ate or drank something with vivid green or blue coloring, that’s very likely your answer.
Chlorophyll supplements, which have become popular as a wellness trend, can do the same thing. The green pigment passes through your system and shows up in the toilet. This is completely harmless and will clear up once the dye or supplement works its way out, typically within a day or two.
Medications That Turn Urine Green
A surprisingly long list of medications can cause green urine. Some of the most well-known culprits include:
- Propofol: an anesthetic used during surgery. It produces green urine in less than 1% of patients as the body breaks it down and excretes byproducts through the kidneys. These byproducts are biologically inactive and do not harm the kidneys at all.
- Indomethacin: a pain reliever and anti-inflammatory.
- Amitriptyline: an antidepressant.
- Cimetidine: a heartburn medication.
- Promethazine: an anti-nausea drug.
- Metoclopramide: another anti-nausea medication.
Many of these drugs contain chemical groups called phenols, which the liver processes and the kidneys excrete, giving urine a greenish tint. Medications containing methylene blue, a dye sometimes used in diagnostic procedures or found in certain urinary tract medications, can also turn urine blue-green.
If you recently started a new medication or had a surgical procedure and then noticed green urine, the medication is almost certainly responsible. The color change reverses after you stop taking the drug. It does not mean your kidneys are damaged.
When Green Urine Signals an Infection
This is the scenario that actually warrants concern. Urinary tract infections caused by a bacterium called Pseudomonas can turn urine green. The bacteria produce pigments as they grow, and those pigments discolor the urine. Pseudomonas infections are more common in people who are hospitalized, have catheters, or have weakened immune systems, but they can occur in otherwise healthy people too.
The difference between a harmless cause and an infection is usually obvious from your other symptoms. A Pseudomonas UTI will typically come with burning during urination, frequent urges to urinate, cloudy or foul-smelling urine, pelvic pain, or fever. Green urine without any of these symptoms is far less likely to be an infection. If you do have these symptoms alongside green urine, you need a urine culture to identify the specific bacteria so it can be treated with the right antibiotic.
Liver and Bile Problems
In people with chronic obstructive jaundice, where bile flow from the liver is blocked, a compound called biliverdin can build up and spill into the urine. Biliverdin is a byproduct of the normal breakdown of red blood cells, and when it can’t drain properly through the bile ducts, the kidneys take over and excrete it, giving urine a green hue.
This is a less common cause and wouldn’t appear out of nowhere. You’d likely already know something was wrong because obstructive jaundice comes with yellowing of the skin and eyes, pale stools, dark urine that shifts toward green, itching, and abdominal pain. If green urine appears alongside any of these signs, it points to a liver or gallbladder issue that needs prompt evaluation.
Rare Causes in Infants
A very rare genetic condition called blue diaper syndrome can cause blue-green discoloration in infants. The syndrome involves abnormal calcium metabolism and is named for the distinctive staining it leaves on diapers. In some cases, the discoloration comes from pigments produced by Pseudomonas bacteria in the stool rather than a metabolic process in the urine itself. This is exceedingly rare and typically identified early in infancy.
How to Figure Out Your Cause
Start with the simplest explanation. Think back over the past 24 to 48 hours: did you eat anything with bright food coloring? Start a new medication? Take a chlorophyll or greens supplement? Have a medical procedure involving anesthesia? If the answer to any of these is yes, and you feel fine otherwise, the green color is almost certainly benign and will resolve once the substance clears your system.
If you can’t trace it to food, dye, or medication, or if the green urine persists beyond a couple of days, a basic urinalysis is the standard first step. A dipstick test can quickly check for signs of infection or elevated bilirubin. If infection is suspected, a urine culture identifies the specific bacteria. More advanced testing, like spectrophotometry or chromatography, exists for unusual metabolic conditions, but these are rarely needed and typically reserved for cases where simpler tests haven’t provided an answer.
The bottom line: green urine that shows up once, lines up with something you ate or a medication you’re taking, and comes with no other symptoms is not dangerous. Green urine that persists for days, comes with pain or fever, or appears alongside signs of jaundice deserves a closer look.