The endocannabinoid system has been implicated in the pathophysiology of multiple sclerosis (MS), yet its role across different disease stages and under disease-modifying treatment remains incompletely understood. This study aimed to evaluate plasma levels of anandamide (AEA) and 2-arachidonoylglycerol (2-AG) in patients with MS at different clinical stages, and to explore their associations with disability, cognition, and quality of life, as well as the potential influence of teriflunomide therapy. Thirty participants were enrolled: ten healthy controls, ten newly diagnosed relapsing–remitting MS (RRMS) patients in acute relapse, and ten teriflunomide-treated RRMS patients in remission. Plasma AEA and 2-AG were measured by ELISA; clinical assessments included the Mini-Mental State Examination (MMSE) and the SF-36 quality-of-life questionnaire. No significant group differences were observed overall in 2-AG (P > 0.05). AEA showed a non-significant overall group effect (ANOVA, P = 0.0919) with a trend toward lower AEA in newly diagnosed patients compared to healthy controls (mean difference = −5.95 ng/ml, SE = 2.66; P = 0.098). In the teriflunomide group, AEA and 2-AG were strongly positively correlated (r = 0.882, P < 0.001). Additionally, SF-36 scores were positively associated with MMSE (r = 0.706, P = 0.023). Furthermore, SF-36 total scores were significantly lower in newly diagnosed patients compared to controls (post-hoc P = 0.044). These findings suggest possible early dysregulation of the endocannabinoid system in MS and indicate that teriflunomide treatment is associated with a strengthened AEA–2-AG relationship. Larger, longitudinal studies are warranted to confirm these observations and to assess clinical implications for disease progression and patient quality of life.