From the Guidelines
Urine color can be changed by various factors, including diet, medications, and medical conditions, with foods and medications being common causes of temporary color changes, as noted in studies on hematuria 1. When considering the potential causes of changes in urine color, it's essential to evaluate the patient's history, including dietary habits, medication use, and any underlying medical conditions.
- Foods like beets, blackberries, and rhubarb can temporarily turn urine pink or red due to their pigment content.
- Medications such as rifampin, phenazopyridine (Pyridium), and certain laxatives can cause orange, bright red, or brown coloration, as they or their metabolites are excreted in the urine.
- Dehydration typically makes urine darker yellow or amber, while proper hydration results in pale yellow urine, highlighting the importance of hydration status in urine color.
- Medical conditions that may alter urine color include urinary tract infections (cloudy urine), liver disease (dark brown urine), kidney stones (pink or red from blood), and hepatitis (dark brown), as these conditions can introduce abnormal substances into the urine. According to the study on hematuria 1, factitious causes of “hematuria,” such as food substances or medicines coloring the urine without actually having red blood cells in the urine, should also be investigated, emphasizing the need to consider non-pathological causes of urine color changes. It's crucial to consult a healthcare provider if persistent unusual urine color is observed, especially red or brown urine not explained by diet or medications, as it could indicate a serious condition requiring treatment, such as glomerulonephritis or other renal diseases discussed in the context of hematuria evaluation 1.
From the FDA Drug Label
Patients should be informed that Phenazopyridine HCl produces a reddish-orange discoloration of the urine and may stain fabric Brownish-red or orange discoloration of the skin, urine, sweat, saliva, tears and feces will occur, and its intensity is proportional to the amount ingested.
Substances that can change urine color include:
- Phenazopyridine HCl which produces a reddish-orange discoloration of the urine 2
- Rifampicin which can cause brownish-red or orange discoloration of the urine 3
From the Research
Factors Affecting Urine Color
- Variables that affect urine color include concentration, pH, ingested substances, and various metabolic abnormalities 4
- Medications, foods, occupation, and family history can also influence urine color 4, 5
- Certain medications, such as metronidazole, can cause urine discoloration as a side effect 6
- Dietary factors, including consumption of certain foods and dietary supplements, can alter urine color 7
Specific Substances and Conditions
- Niridazole, a medication used to treat Schistosoma mansoni infection, can cause red/brown urine pigment 8
- Metronidazole, an antibiotic, can cause urine discoloration, including cola-colored urine 6
- Intensive physical exercise, inadequate hydration, and certain diseases can also affect urine color 7
Diagnostic Approach
- A careful history and urinalysis can help determine the cause of abnormal urine color 4, 5
- Gross examination of the urine, specific gravity, pH, dipstick, and microscopic examinations can aid in diagnosis 4
- Further testing, such as ferric chloride or ultraviolet (UV) light source, may be necessary to narrow down the differential diagnosis 4