What Causes Green Urine?

Green urine is an uncommon but clinically notable phenomenon that can arise from a variety of causes—ranging from benign and transient to potentially indicative of underlying pathology. While urine color is typically pale yellow due to the pigment urochrome, deviations—including greenish or blue-green hues—warrant thoughtful evaluation.

One of the most frequent non-pathological explanations is dietary or pharmacologic exposure. Certain food dyes—particularly those found in brightly colored candies, beverages, or ice pops—can impart a green tint. Similarly, several medications are well-documented to cause green urine discoloration, including propofol (an intravenous anesthetic), amitriptyline (a tricyclic antidepressant), cimetidine (an H2-receptor antagonist), indomethacin (a nonsteroidal anti-inflammatory drug), and the antibiotic ciprofloxacin. These agents either contain blue or green dyes or undergo hepatic metabolism into pigmented metabolites excreted renally.

Infectious etiologies must also be considered. Pseudomonas aeruginosa urinary tract infections (UTIs) are classically associated with green-tinged urine due to the production of pyocyanin, a blue-green phenazine pigment secreted by the organism. This finding may accompany symptoms such as dysuria, urgency, suprapubic discomfort, or fever—and warrants prompt urine culture and targeted antimicrobial therapy.

Rare metabolic or genetic conditions may also contribute. Familial hypercalcemia with hypocalciuria (FHH) has been linked to green urine in isolated case reports, though the mechanism remains unclear. Additionally, disorders affecting bilirubin or porphyrin metabolism—such as certain types of porphyria—can occasionally result in unusual urine colors, including greenish or brownish hues, especially when exposed to light.

Clinicians should approach green urine with a detailed history—including recent medication use, dietary intake, symptom onset, and associated systemic features—followed by urinalysis and, when indicated, urine culture, serum electrolytes, and liver function tests. In most cases, green discoloration is harmless and resolves spontaneously upon discontinuation of the inciting agent; however, persistent or symptomatic green urine necessitates further diagnostic workup to exclude infection or metabolic disease.