Background: As per National Institute for Health and Care Excellence (NICE) guidelines, depression and anxiety are common mental health disorders. Antidepressants are used in the treatment of these disorders. It is well acknowledged that antidepressants can lead to Adverse Drug Reactions (ADRs). Comprehending the common ADRs linked to antidepressants is beneficial for improving patient safety, promoting rational prescribing practices and encouraging enhanced adherence to treatment. Purpose: To analyze the incidence of adverse drug reactions and evaluate their causality, severity and predictability for medications utilized in the treatment of common mental health disorders. Materials and Methods: This prospective longitudinal observational study was conducted in a tertiary care teaching hospital in Puducherry from July 2020 to November 2023. The participants were patients diagnosed with a common mental health disorder as per DSM-5. Participants were monitored for ADRs during every follow-up visit for 6 months from the baseline visit. Results: This research enrolled 216 patients and data from 144 patients who attended at least one follow-up appointment during the six-month follow-up period were included in the analysis. The overall incidence rate of ADRs was found to be 38.2%. Selective Serotonin Inhibitors (SSRIs) contributed to over 60% of the reported ADRs. The majority of reactions were classified as possible (85.8%) in causality assessment and a noteworthy proportion of these reactions were mild (63.2%) and predictable (91.5%). Conclusion: The research reveals a 38.2% incidence rate of ADRs. Majority of the ADRs were 'possible' , 'mild' and 'predictable' . Ongoing surveillance can aid in the detection, mitigation and prevention of ADRs.