Effects of 940 nm low-level laser therapy for the treatment of primary dysmenorrhea: a double-blind, randomized, placebo-controlled trial

Abstract

Abstract Background: Primary dysmenorrhea (PD) is one of the most common and disturbing gynecological disorders, and effective nonpharmacological treatments are still in urgent demand. low-level laser therapy (LLLT) showed wide application prospects in pain management. This study aimed to assess the therapeutic effects and safety of 940nm LLLT for PD. Methods: 100 participants with PD were allocated at random (2:1) to the LLLT group (n=68) or the control group (n=32) and treated with 940nm LLLT at the Guan Yuan acupoint or placebo for 30 minutes once daily before menstruation onset. Participants were treated for three menstrual cycles (T1, T2, T3) and followed up for another three cycles (T4, T5, T6). Visual analogue scale (VAS), Abdominal pain time (APT), Abdominal pain degree (APD), COX menstrual symptom scale (CMSS), Self-rating anxiety Scale (SAS), Self-rating depression scale (SDS), rescue medicine usage and complications at each menstrual cycle were recorded and compared. Change of VAS, APT, APD, CMSS, SAS and SDS from baseline at T3 was compared with those at T1 and T2. Results: Compared with baseline, VAS, APT, APD, CMSS, SAS and SDS were significantly decreased at all menstrual cycles in the LLLT group (except APT and SAS at T5-6). Compared with the control group, VAS at T1-5, APT and SDS at T2-4, APD and CMSS at T1-6, and SAS at T1-4 were found significantly lower in the LLLT group. Compared with T1 or T2, greater improvement from baseline was found in all parameters in the LLLT group at T3 (except APD and SAS with T2). The rate of rescue medication use in the LLLT group was significantly lower than that in the control group at T3 and T6. No adverse reaction was found. Conclusion: 940nm LLLT is a safe and promise complementary method for PD treatment with a cumulative feature of therapeutic effect. Trial registration: ChiCTR2100046199, 09/05/2021.