This study compared the safety and efficacy of the on-demand (OD) use of sertraline (50 mg), sertraline (100 mg) and dapoxetine (30 mg), and the daily use of sertraline (50 mg) in the treatment of patients with premature ejaculation (PE). This prospective randomised study involved 120 lifelong PE patients (intravaginal ejaculatory latency time [IELT]: <1 min; Arabic Index of Premature Ejaculation [AIPE] score: < 30) without secondary causes of PE, identified between March 2018 and May 2020. Patients were divided into 4 groups (30 patients per group) and treated for 8 weeks. Assessments were conducted using the AIPE form as a diagnostic tool. Sertraline (50 mg, daily; 196.7 +/- 115.5 s) and sertraline (100 mg, OD; 173.3 +/- 97.0 s) had similar IELT and AIPE scores. The latter groups had better results in comparison with sertraline (50 mg, OD; 100.5 +/- 54.4 s) and dapoxetine (93.7 +/- 53.5 s; p < 0.01). Sertraline (100 mg, OD) had a similar efficacy to that of sertraline (50 mg, daily) and was more effective than sertraline (50 mg, OD) and dapoxetine (30 mg, OD). Sertraline (100 mg, OD) can be considered in the treatment of lifelong PE treatment, having tolerable side effects.