Dysmenorrhea is one of the most prevalent gynecological conditions among females of
reproductive age and is associated with substantial physical, psychological, and socioeconomic
consequences. Previous studies have largely relied on cross-sectional designs, limiting causal
inference and clinical differentiation between primary and secondary dysmenorrhea. The
present longitudinal study aimed to evaluate the temporal patterns, determinants, and quality of life impact of dysmenorrhea while clinically distinguishing primary and secondary forms. A cohort of females aged 12–45 years was followed for twelve consecutive menstrual cycles. Pain severity, anthropometric parameters, medication use, absenteeism, and quality-of-life indicators were assessed using validated instruments, alongside clinical evaluation to identify secondary causes. Results indicated that dysmenorrhea severity and its impact on daily functioning vary over time and are influenced by body mass index, age at menarche, stress levels, and medication practices. Secondary dysmenorrhea was associated with higher pain intensity and greater impairment in academic and occupational performance. These findings highlight the necessity of longitudinal monitoring and early clinical differentiation to improve dysmenorrhea management and reduce its long-term burden.