BACKGROUND: The effects of tPBMT are from influencing compounds by triggering specific reactions, which stimulate Adenosine triphosphate biosynthesis and neurogenesis. According to these effects, tPBMT has been applied as a potential treatment for various neural-related diseases. The purpose of this study was to evaluate the impact of tPBMT on reducing anxiety, depression, and opioid craving in patients undergoing MMT. METHODS: This randomized controlled clinical trial included two groups of substance-dependent patients undergoing MMT. They were randomly assigned to receive tPBMT or a sham tPBMT. The intervention group received PBM in the form of Light- Emitting Diodes (LEDs) for four minutes of light exposure at 810 nm wavelength producing 250 mW/cm RESULTS: Both groups consisted of 32 (91.4%) males and 3 (8.6%) females, with the mean age of patients in the intervention group being 37.97 ± 10.58 years, and 39.66 ± 9.94 years in the control group (P = 0.495). There were no significant differences between the two groups in terms of depression, anxiety, and opioid craving scale scores before the intervention (p>
0.05). However, the tPBMT group had statistically significant reductions in their scores compared to the sham tPBMT group. (p<
0.05). CONCLUSION: tPBMT led to significant improvements in anxiety, depression, and opioid craving among individuals in MMT, and these improvements were sustained at one month and three months after treatment, indicating a long-lasting positive effect. TRIAL REGISTRATION: Trial registration: IRCT code: IRCT20210502051162N1, Approval ID: IR.SBMU.MSP.REC.1400.111, registered on 01.06.2021.