Although Pakistan has a high burden of multidrug-resistant tuberculosis (MDR-TB), little is known about prevalence, management, and risk factors for adverse drug reactions (ADRs) in MDR-TB patients in Pakistan. To evaluate occurrence, management, and risk factors for ADRs in MDR-TB patients, and its impact on treatment outcomes, this observational cohort study was conducted at programmatic management unit for drug resistant TB of Lady Reading Hospital Peshawar, Pakistan. A total of 181 MDR-TB patients enrolled at the study site from January 1, 2012 to February 28, 2013 were included. Patients with drug resistant TB other than MDR-TB, transferred out patients and those who were still on treatment at the end of study duration (January 31, 2015) were excluded. Patients were followed until treatment outcomes were reported. ADRs were determined by laboratory data and/or clinical criteria. SPSS 16 was used for data analysis. A total of 131 patients (72.4%) experienced at least 1 ADR. Gastrointestinal disturbance was the most commonly observed adverse event (42%), followed by psychiatric disturbance (29.3%), arthralgia (24.3%), and ototoxicity (21%). Potentially life-threatening ADRs, such as nephrotoxicity (2.7%) and hypokalemia (2.8%) were relatively less prevalent. Owing to ADRs, treatment regimen was modified in 20 (11%) patients. On multivariate analysis, the only risk factor for ADRs was baseline body weight ≥ 40 kg (OR = 2.321, P-value = 0.013). ADRs neither led to permanent discontinuation of treatment nor adversely affected treatment outcomes. Adverse effects were prevalent in current cohort, but caused minimal modification of treatment regimen, and did not negatively impact treatment outcomes. Patient with baseline body weight ≥ 40 kg should be closely monitored.