A study conducted in Tehran, Iran, assessed the impact of the COVID-19 pandemic on methadone maintenance therapy (MMT) for addiction treatment. Researchers analyzed data from 180 MMT patients across four treatment centers, comparing methadone intake and behavioral patterns before and during the pandemic. The average methadone dose increased from 54.16 mg to 62.09 mg, with 57 patients increasing their intake by an average of 35.79 mg, while 14 patients reduced their intake by 37.15 mg. Living with family was identified as a risk factor for dose escalation, while pre-existing illness and being aged 40 to 50 were protective factors. Behavioral changes included 21.1% of patients reporting increased drug cravings, 14.4% slipping to other substances, and 94.4% being smokers with high nicotine dependence. Additionally, 10% reported decreased physical activity, while many increased their mobile and internet usage, with 28.3% experiencing high anxiety levels. The findings indicate that while methadone dispensing practices remained stable, the pandemic negatively affected patient behaviors and psychological well-being. Recommendations include enhancing telehealth services and integrating mental health support to ensure continuity of care during future public health crises.