Discoloration of body fluids is a known effect of which tuberculosis drug?

• A. Isoniazid
• B. Rifampin
• C. Ethambutol
• D. Pyrazinamide

Answer: (B)

Rifampin commonly produces orange-red discoloration of body fluids such as urine, tears, and sweat. This harmless staining comes from the pigment in the drug and can even stain contact lenses or fabrics. It’s a distinctive sign that helps identify rifampin use, not an indication of toxicity. Other TB drugs don’t routinely cause this specific fluid discoloration: isoniazid is more associated with hepatotoxicity and neuropathy, ethambutol with optic neuritis and color-vision changes, and pyrazinamide with hepatotoxicity and hyperuricemia.