Background: Methadone is considered a long-acting opioid agonist which is widely used in the treatment of drug addiction. It is believed that opioids can cause erectile dysfunction (ED) by inhibiting gonadotropin and testosterone release. This study is aimed at defining the possible effects of conservative treatment with methadone on erectile dysfunction in the addicts.
Methods: A total of 382 male addicts visiting methadone maintenance therapy (MMT) centers in Rasht, Iran, during 2010 were enrolled in this study. International Index of Erectile Function (IIEF) questionnaire and patients' profiles were the main means of collecting data on demographic information, methadone dose intake, and erectile function status before and after the two months of therapy with methadone. Erectile function status was defined by the total score from questions 1, 2, 3, 4, 5, and 15 of the questionnaire. The data was analyzed by X2, McNemer’s test, and paired t-test using SPSS software 18.
Results: The mean age of patients was 37.6 ± 8.9 years (range: 18-72 years). Most of the patients were married (79.3%) and they were citizens of Rasht (72.3%). The most frequent substances were opium (188 patients, 49.2%) and crack (129 patients, 33.8%), respectively. Most of the patients received low dose methadone (286 patients, 74.9%). No significant relationship was indicated comparing the average scores of erectile function before and after taking methadone (18.53±6.978 vs. 19.03±5.819) (P=0.138). However, the severity of erectile dysfunction was significantly related to the methadone intake dose (P<0.001).
 Conclusion: Although MMT increases the frequency of erectile dysfunction, appropriate doses of methadone minimize this effect.