Background: Tuberculosis (TB), an infectious disease caused by Mycobacterium tuberculosis, is the second leading infectious cause of death in the world. The objective was to study the demographic details of the tuberculosis patients experiencing adverse drug reactions (ADRs) and to identify the frequency of adverse drug reactions. Materials and Methods: : It was a prospective observational study conducted in pulmonology department of Institute of Chest Disease, Govt. Medical College, Kozhikode, Kerala, India. All the TB patients admitted at the directly observed treatment, short course (DOTS) Center at Medical College Hospital were enrolled and were monitored for ADRs. The causality and severity of the reactions were determined using Naranjo algorithm and Hartwig question-naire, respectively. Results: A total of 511 tuberculosis patients who were on DOTS therapy were enrolled for the study. Out of 511 pa-tients, 93 patients (18.20%) developed adverse drug reactions. The higher numbers of ADRs were observed in males (68.81%) and the remaining (31.18%) was observed in female. Diabetes mellitus (41.02%) was the most common comorbidity. Most of the ADR occurred in the intensive phase (85.71%) of treatment. It was observed that pulmonary TB (55.18%) was more common than extra pulmonary TB. Majority of adverse drug reactions were gastrointestinal (GI) problems (38.09%). The most serious ADR was hepatitis. Isoniazid was the major drug which caused 34.40% of adverse drug reactions. Conclusion: About 17.02% people developed different type of ADRs during the study period. As a pharmacist we have the liability to support the patients during the period of antitubercular treatment. These ADR may steer the patient to make a judgment for stopping the medications and finally the occurrence of drug resistance and an amplified healthcare cost. If a proper educational system is implemented, most of the patients may report their ADR and thereby we can improve the patient adherence and therapeutic outcome.