Hypertension is one of the main factors contributing to the global burden of non-communicable diseases. Previous research has revealed that stress, bad lifestyle choices and a lack of knowledge about the disease are the main causes of hypertension that can be controlled. The key cause behind the prevalence of the condition is the lack of medication adherence by patients. This study aims to evaluate medication adherence in patients with hypertension through the Morisky Medication Adherence Scale (MMAS) and to observe any adverse drug reaction leading to non-adherence of medications. A descriptive, cross-sectional study was conducted on 124 patients who attended the outpatient department of medicine. The descriptive tools were MMAS and causality scales for adverse drug reactions. The mean MMAS score was 5.20±1.29. Amongst the demographic profile, age, sex, comorbidities and duration of disease were significantly associated with decreased mean MMAS scores. Forty-two patients experienced drug reactions and only four patients were adherent to their medications. Our study suggests that patients were poorly adherent to their medications. Effective interventions should be considered to improve adherence in patients. Monitoring for adverse drug reactions can lead to improved patient outcomes, whilst interventions to improve adherence can lead to better blood pressure control and reduced risk of cardiovascular events.