Neon green pee is almost always caused by excess B vitamins, specifically riboflavin (vitamin B2), being flushed out through your kidneys. If you recently took a multivitamin, a B-complex supplement, or drank an energy drink, that’s your answer. Your body absorbed what it needed and dumped the rest into your urine, where riboflavin’s natural fluorescent properties create that startling glow.
Why B Vitamins Do This
Riboflavin is a water-soluble vitamin, which means your body can’t store much of it. When you take in more than you need, the excess passes straight through your kidneys into your urine within a few hours. What makes riboflavin unique is its chemical structure: it naturally fluoresces, producing a vivid yellow-green color even in small concentrations. Researchers actually use this property on purpose in clinical trials, tracking whether participants took their medication by checking for fluorescent urine.
The recommended daily intake of riboflavin is about 1.1 to 1.3 mg for adults. A standard multivitamin typically contains around 1.3 mg. But many B-complex supplements, energy drinks, and pre-workout formulas pack far higher doses. Riboflavin supplements prescribed for migraine prevention, for example, contain 400 mg per day, over 300 times the daily recommendation. At doses like that, the neon effect is guaranteed. Even a regular multivitamin can produce noticeably bright urine if you took it on an empty stomach or are well-hydrated, since the excess clears quickly and concentrates in whatever urine your body produces next.
This color change is harmless. The Mayo Clinic notes that riboflavin-related urine color changes are expected and “no cause for alarm.” It simply means your body is working correctly by excreting what it doesn’t need.
Food Dyes and Certain Foods
If you haven’t taken any supplements, food dyes are the next likely culprit. Brightly colored candies, cereals, sodas, popsicles, energy bars, and sports drinks can contain enough artificial green or blue dye to tint your urine. Blue dyes in particular mix with the natural yellow of urine to produce a green result. The effect is temporary and clears once the dye works through your system, usually within a day.
Medications That Change Urine Color
Several prescription and over-the-counter medications can turn urine green. Some contain compounds called phenol groups that get processed in the liver and excreted by the kidneys as green-tinted byproducts. These include promethazine (an anti-nausea drug), cimetidine (a heartburn medication), and propofol (an anesthetic you’d encounter during surgery). Other medications produce green urine through different pathways: amitriptyline (an antidepressant), indomethacin (an anti-inflammatory), and metoclopramide (used for nausea and digestive issues).
If you recently started a new medication and noticed the change, check the side effects listed on your prescription information. The color change itself is not dangerous, but it’s worth mentioning to your prescriber if it caught you off guard.
When Green Urine Signals a Problem
In rare cases, green urine points to something that needs medical attention. Two conditions stand out.
A urinary tract infection caused by a specific type of bacteria called Pseudomonas can turn urine green. This bacterium produces pigments as it grows. If your green urine comes with burning during urination, fever, cloudy or foul-smelling urine, or pelvic pain, an infection is a real possibility and worth getting checked.
Liver and bile duct problems can also produce green urine. When bile flow is blocked for an extended period (chronic obstructive jaundice), a breakdown product of bile called biliverdin accumulates and gets excreted in urine, giving it a greenish hue. This would typically come alongside other noticeable symptoms like yellowing of the skin or eyes, pale stools, or abdominal pain.
How to Figure Out Your Cause
The simplest test is to think about what you consumed in the last 6 to 12 hours. If you took a multivitamin, B-complex, or energy drink, skip it for a day and see if your urine returns to its normal pale yellow. For most people, the neon color disappears within one to two urination cycles after the supplement clears your system.
If you can’t trace it to a supplement, food, or medication, and especially if you have any pain, fever, or other unusual symptoms alongside the color change, that’s when it makes sense to get a urine test. But for the vast majority of people who Google this question after a morning vitamin and a startling trip to the bathroom, the answer is simple: your body just flushed out extra B2, and everything is working exactly as it should.