• Green pee can be caused by green or blue food dye in things like cereals, ice cream, and candy.
  • If you have a UTI, your urine may appear green because of bacteria called pyocyanin.
  • Green pee may also be an early sign of liver disease or blue diaper syndrome in babies.

If you look into the toilet and see green, you might get startled. Green pee is rare, but in most cases it's not cause for concern, says Dr. Kelly Johnson-Arbor, a toxicologist and medical co-director for the National Capital Poison Center

"Because our kidneys are constantly filtering out waste products from the blood, the color and odor of urine can change on a frequent basis," Johnson-Arbor says. 

Most often, green urine is caused by dyes added to food, medicine, and personal care products like mouthwash, says Dr. Anurag K. Das, chief of urology at Staten Island University Hospital

"But sometimes it could be a more serious issue," including liver disease or a urinary tract infection (UTI), Das says. 

Here are seven possible causes of green pee, and how to deal with each. 

1. Food Dyes

Food dyes, blue and green in particular, are the most common cause of green urine. 

For example, indigo carmine, also known as Blue #2, is a common food dye that can cause green urine, Das says. It's found in breakfast cereals, drinks, ice cream and candy. 

When your body filters those dyes out, they're secreted in your urine, creating the green tinge.

What to do about it: Just wait. Green pee caused by food products will be most vibrant in the six hours after you consume the food. It should resolve entirely within a day or so. 

2. Medications

Like foods, many medications contain colored dyes. So do medical products and anesthetics used during surgery or other in-office medical procedures. These can cause your urine to appear green when they're filtered out of your body. 

Common medications associated with green pee are:

What to do about it: If you have green pee after surgery or a medical procedure, it will likely only last a day or two, until the one-time medication clears your system.

"Don't worry, as this is a benign side effect that should not cause other unwanted symptoms or require specific treatment," Johnson-Arbor says.

However, if you think it's caused by a prescription that you will be taking long term, speak with your doctor, Das says. It's likely harmless, but it's always a good idea to let doctors know about any side effects from new meds. 

3. Personal care products

Personal care products and cosmetics also contain dyes. If you accidentally consume them, they could turn your urine green. 

One example is Listerine mouthwash, which can cause green urine if you accidentally swallow it because of its ingredient thymol, Johnson-Arbor says. Breath mints, cosmetics and other products with blue or green dyes can have a similar effect. 

What to do about it: "Don't be alarmed, as these changes are not harmful to the body," Johnson-Arbor says. "The discoloration should go away after you stop using the products, and it's unlikely that affected individuals will have additional worrisome symptoms or require medical treatment." 

4. Urinary tract infection

Some UTIs are caused by a bacteria called pseudomonas aeruginosa. These bacteria create pyocyanin, a blue-green tinged compound that can leave your urine looking green. If you have a UTI, you'll likely notice other symptoms including:

  • Pain or burning during urination
  • Frequent urination
  • Abdominal and lower back pain
  • Cloudy or foul-smelling urine 
  • Fever

What to do about it: Talk to your doctor. UTIs need to be treated with antibiotics. If they're left untreated, they can lead to serious complications including sepsis, Johnson-Arbor says. 

5. Liver disease

Your urine may appear green if it contains any bilirubin. Bilirubin is a byproduct of the breakdown of red blood cells. In healthy people it's cleared away by the liver, but having bilirubin in your urine can be an early sign of liver disease. 

If this is the cause of your green urine, you'll notice that the green continues over time. You may also experience other symptoms like:

  • Nausea, vomiting, and loss of appetite
  • Fatigue and weakness
  • Swelling in the abdomen, ankles, and legs
  • Itching
  • Jaundice, a yellow tinge to the skin and eyes

What to do: Talk to your doctor and ask for a bilirubin urine test. If bilirubin is in your system your doctor will do additional tests like cirrhosis or blocked bile ducts to diagnose liver disease. Depending on your diagnosis, your doctor will prescribe medications and lifestyle changes As your liver health improves you may notice green urine resolve. 

6. Blue diaper syndrome 

Blue diaper syndrome is a very rare disease that mostly affects babies. 

It happens when the body can't break down tryptophan, a nutrient found in animal-based foods like milk and eggs. Blue diaper syndrome can lead to hypercalcemia, causing blue or green-tinged urine. 

A child with blue diaper syndrome might have trouble gaining weight, or be diagnosed with failure to thrive, a condition where a baby is not gaining weight or meeting developmental milestones. Diarrhea, vomiting, and changes to appetite are also symptoms. 

What to do about it: Talk to your baby's pediatrician. They may be able to diagnose the disease based on a urine sample. People with blue diaper syndrome need to eat a diet low in calcium, protein and vitamin D. 

When to see a doctor

It's normal to see an array of colors when you look into the toilet after peeing. Most of them — whether they're green or another color — are entirely normal. Others should prompt a call to your doctor. 

"While many causes of urine discoloration are benign and are caused by foods or medications, some urinary color changes warrant medical attention," Johnson-Arbor says. 

Red or brown urine can indicate blood in the urine. That's associated with serious conditions including kidney stones, infections, and even cancer. Even if you have blood one time, call your doctor. 

In addition, you should call your doctor if you:

  • Suddenly have a strange urine color that doesn't go away after a day or so. 
  • Have urine that smells foul.
  • Notice green or blue urine from your child.
  • Have symptoms including fever or weakness.

Insider's takeaway

Green urine can be alarming, but in almost all cases it's nothing to be concerned about. 

"The most common cause of green-colored urine is products that are consumed such as dyes and personal care products," Johnson-Arbor says. If that's the case, your urine will be back to normal within a day or so. 

However, if your urine stays green and you experience any other symptoms like pain while urinating, fatigue or changes to appetite, talk with your doctor. 

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