Background: The aim of management of acute low back pain is to alleviate the pain quickly and improve functional ability. Non-steroidal anti-inflammatory drugs are the first line of treatment. The challenge lies in deciding which NSAIDs will provide greater symptomatic relief, while also being cost-effective. Objective: To compare the effectiveness of aceclofenac and etoricoxib in the management of acute low back pain. Methods: This prospective, open label, observational study was conducted at a tertiary care hospital. Patients over 18 years of age and presenting with low back pain of less than 6 weeks duration were enrolled in the study. Fifty patients with non-specific low back pain were randomized into two groups: Group A received aceclofenac (2 mg/kg) twice a day and Group B received etoricoxib (1 mg/kg) twice a day for 1 week. The Numerical Rating Scale (NRS) and Oswestry Low Back Disability Index (ODI) determined the clinically meaningful outcomes. Results: The decrease in pain intensity in Group A was 52.27%, while in Group B it was 62.53%. However, the decrease in pain scores between the groups was not statistically significant (p ¼ .3795). Improvement in functional ability in Group A and Group B was 57.01% and 61.48%, respectively. However, this improvement between the groups was not statistically significant (p > .999) at the end of 1 week. The average cost-effectiveness ratio indicated that etoricoxib was the dominant treatment over aceclofenac. Therefore, etoricoxib was found to be the cost-effective option for short-term pain relief in acute low back pain for 1 week. Conclusion: Both aceclofenac and etoricoxib were clinically effective in reducing the pain intensity and in improving functional ability. However, etoricoxib was found to be the cost-effective intervention.