Rifampin Causes Red-Orange Urine Discoloration
Rifampin is the anti-tuberculosis drug that causes red-orange discoloration of urine, along with other body fluids including tears, sweat, sputum, and saliva. 1, 2
Mechanism and Clinical Presentation
Rifampin is excreted in urine, tears, sweat, and other body fluids, causing them to turn orange, red, yellow, or brown in color. 1, 2 This discoloration is:
- An expected, benign effect that does not indicate toxicity or require discontinuation of the drug 1
- Useful for monitoring compliance, as the urine can be assessed visually or checked in the laboratory for orange/pink coloration 1
- Permanent for soft contact lenses, which may be irreversibly stained 1, 2
Practical Clinical Applications
Patient Counseling
Patients must be forewarned that rifampin will produce discoloration (yellow, orange, red, brown) of teeth, urine, sweat, sputum, and tears. 2 This counseling should occur before initiating therapy to prevent unnecessary alarm and ensure medication adherence.
Compliance Monitoring
The orange/pink urine coloration serves as a practical tool to verify medication adherence, particularly when directly observed therapy is not feasible. 1 Combined rifampin preparations (Rifinah, Rifater) provide this built-in compliance check mechanism. 1
Urine-Based Therapeutic Monitoring
Recent research demonstrates that urine spectrophotometry can detect rifampin underexposure with an area under the ROC curve of 0.80-0.84 for predicting subtarget serum concentrations. 3 Urine collected 0-4 hours or 0-8 hours after dosing accurately identifies patients with inadequate drug exposure, offering a simpler alternative to serum-based monitoring. 3
Important Distinctions from Other TB Medications
- Isoniazid: Does not cause urine discoloration 1
- Pyrazinamide: Does not cause urine discoloration 1
- Ethambutol: Does not cause urine discoloration 1
- Rifabutin: Also causes orange discoloration of body fluids, similar to rifampin 1
Common Pitfalls to Avoid
Do not mistake urine discoloration for hematuria or other pathology. The orange-red color from rifampin is distinct and expected, not a sign of adverse reaction requiring drug discontinuation. 1, 2
Do not fail to warn patients about permanent staining of soft contact lenses. Patients should be advised to use alternative vision correction during rifampin therapy or accept permanent lens discoloration. 1, 2
Do not overlook the utility of urine color as a compliance indicator. Absence of urine discoloration in a patient supposedly taking rifampin suggests non-adherence and warrants investigation. 1