Objective: The objective was to study the adverse drug reactions (ADRs) associated with first–line anti–tubercular drugs for clinical presentations, causality, and severity. Methods: A retrospective study was undertaken in a tertiary care teaching hospital of India for the duration of 1 year (January 2019 – December 2019). Patients diagnosed with tuberculosis and under treatment with the first–line anti–tubercular drugs were study subjects. Causality, outcome and severity were analyzed and other parameters such as male to female ratio, most affected system, , and common types of ADRs, were studied. Results: Nearly 130 patients were started on anti–tubercular treatment of first–line drugs in the study duration. Out of these 60 patients suffered one or more ADRs with a total number of reported ADRs being 105. 67% were males. Maximum patients belonged to the age group of 31–40 years (30%). The most commonly involved system was hepatic and biliary system (60%) followed by gastrointestinal system (40%), the most common ADR observed was disturbed liver transaminases (40%) followed by nausea and vomiting (25%). Causality assessment by Naranjo’s scale showed 60% ADRs scoring probable, 25% were of possible score, whereas 15% definite score category. Severity assessment shows 66% cases of mild grading, 32% of moderate and 2% cases of severe grading was reported in the study duration Conclusions: Vigilance regarding these ADRs occurrences can result in early diagnosis and thus, proper management can be instituted earliest. This will build confidence of patients and will decrease the dropouts which in turn can result in decrease chances of developing drug–resistant strains.