 In this study, we will study three regimes of re-introduction of hepatotoxic anti-tuberculosis drugs Rifampicin, Isoniazide, Pyrazinamide. These are potent anti-tuberculosis medications and need to be restarted in patients who developed liver toxicities attributed to these medications and became normal when these medicines were stopped. At the time of re-introduction the patients will be randomized in 3 groups. 