A 32-year-old man from rural Maharashtra is diagnosed with pulmonary tuberculosis (sputum smear-positive). He is started on standard first-line therapy. Regarding adverse effects and monitoring during anti-TB treatment, all of the following are correct EXCEPT:

Explanation

## Adverse Effects of First-Line Anti-TB Drugs ### Detailed Comparison | Drug | Major Adverse Effect | Mechanism | Management | |------|---------------------|-----------|------------| | Isoniazid | Peripheral neuropathy | Pyridoxine antagonism | Pyridoxine 10 mg/day prophylaxis | | Rifampicin | Orange-red discoloration of body fluids | Normal pharmacological effect, NOT hepatotoxicity | Reassurance; continue therapy | | Pyrazinamide | Hyperuricemia, gout | Inhibits renal urate excretion | Monitor uric acid; allopurinol if needed | | Ethambutol | Optic neuritis (red-green color blindness) | Direct retrobulbar nerve toxicity | Baseline + monthly visual acuity testing | ### Key Point: **Orange-red discoloration of body fluids caused by rifampicin is NOT a sign of hepatotoxicity.** It is a benign, expected pharmacological effect due to the drug's lipophilic nature and is completely reversible. Patients must be counseled about this to prevent unnecessary anxiety and drug discontinuation. ### High-Yield: **Rifampicin's orange discoloration:** - Affects urine, tears, sweat, sputum, and saliva - Reversible upon drug discontinuation - Does NOT indicate liver damage - Common cause of non-adherence if not explained ### Clinical Pearl: True hepatotoxicity from anti-TB drugs (INH, RIF, PZA) presents with elevated transaminases, jaundice, and constitutional symptoms — NOT color change alone. The combination of INH + RIF + PZA carries the highest hepatotoxicity risk (2–3% incidence). ### Warning: ~~Orange discoloration = hepatotoxicity~~ — it is a benign cosmetic effect. Do not confuse with actual liver injury, which requires LFT monitoring and possible drug modification.