Cranberry Supplements and Urine Color
Cranberry supplements do not typically cause a change in urine color, and this is not documented as a side effect in clinical trials or guidelines. The extensive clinical evidence examining cranberry products for UTI prevention has not routinely reported urine discoloration as an adverse effect 1, 2.
Evidence from Clinical Trials
The most recent and comprehensive evidence comes from multiple high-quality sources:
The 2025 AUA/CUA/SUFU guidelines explicitly state that "clinical studies have also not routinely reported side effects, but the available evidence suggests the potential harms from cranberry use are minimal" 1. These guidelines reviewed decades of cranberry research across various formulations (juice, cocktail, and tablets) and made no mention of urine color changes.
A 2023 Cochrane systematic review analyzing 50 studies with 8,857 participants found that gastrointestinal side effects were the primary concern, with no documentation of urine discoloration 3.
A 2025 multicenter RCT with 150 participants taking 500 mg/day of whole cranberry powder for 6 months reported "no safety concerns" without any mention of urine color changes 4.
Important Clinical Caveat
If a patient reports cranberry-colored or reddish urine, this warrants evaluation for hematuria or hemoglobinuria rather than attribution to cranberry supplements. One case report describes a patient with "cranberry-colored urine" that was ultimately diagnosed as hemoglobinuria from paroxysmal nocturnal hemoglobinuria, initially misdiagnosed as hematuria 5. This highlights that discolored urine described as "cranberry-colored" is a clinical finding requiring investigation, not an expected effect of cranberry consumption.
Mechanism Considerations
Cranberries work through proanthocyanidins (PACs) that prevent bacterial adhesion to the urothelium 1. This mechanism does not involve pigment excretion that would alter urine color. The recommended therapeutic dose of at least 36 mg PACs has been extensively studied without reports of urine discoloration 1.
Bottom line: Reassure patients that cranberry supplements should not change their urine color, and investigate any reported urine discoloration as you would in any other clinical context.