From the Guidelines
Green urine is most likely caused by the use of methylene blue, a dye-based contrast agent, which can result in a green hue to the urine due to its renal excretion. This is based on the study by the american gastroenterological association (aga) institute technology assessment on image-enhanced endoscopy 1. The study highlights that methylene blue staining can persist for up to 24 hours until complete renal excretion, leading to a green discoloration of the urine.
Some key points to consider when evaluating green urine include:
- Certain medications, such as methylene blue, can cause urine discoloration due to their pigment properties
- Foods with strong pigments, like asparagus, may also contribute to greenish urine
- Medical conditions, including urinary tract infections caused by Pseudomonas bacteria or liver and bile duct problems, can produce green urine
- Persistent green discoloration without an obvious cause warrants medical evaluation to rule out underlying conditions
It is essential to note that while occasional green urine from food or medication is usually harmless, persistent or accompanied by concerning symptoms, such as pain or fever, requires prompt medical attention. Proper hydration can help dilute urine and reduce the intensity of unusual coloration, but it is crucial to address the underlying cause of the discoloration. As stated in the study 1, methylene blue is a common cause of green urine, and its use should be considered when evaluating patients with this symptom.
From the FDA Drug Label
The FDA drug label does not answer the question.
From the Research
Causes of Green Urine
- Exogenous substances such as medications, food colorings, and traditional Chinese medicines can cause green urine discoloration 2, 3, 4
- Specific medications associated with green urine include:
- Infections such as pseudomonas can also cause green urine 3
- A bezoar effect, where methylene blue is retained in the bowel and then reabsorbed, can also lead to green urine 5
- Renal failure can cause a delay in the appearance of methylene blue in the urine, leading to green discoloration 6