A patient with tuberculosis is taking standard anti-TB medications. Which drug in the regimen is most associated with a concerning side effect, and what is it?

Isoniazid (INH) is the most commonly used anti-tuberculosis drug and is well known for causing drug-induced hepatitis (hepatotoxicity). The incidence increases with age and alcoholism. INH also causes peripheral neuropathy due to pyridoxine (vitamin B6) deficiency — for this reason, pyridoxine is co-administered. Rifampin can cause hepatotoxicity as well but also causes drug interactions (potent CYP450 inducer), reddish-orange discoloration of body fluids, and flu-like syndrome. Ethambutol causes optic neuritis (not anemia). Pyrazinamide causes hepatotoxicity and hyperuricemia.