If prolonged side effects occur, our medical staff is on-site daily to evaluate and advise patients. Methadone can also affect the effectiveness of medications you may currently be taking for other medical conditions; therefore, it is important to keep all of your doctors/dentists informed about medications you are taking. The combination of methadone and benzodiazepines (Xanax™, Klonopin™, Valium™, etc.) is particularly dangerous, as the body’s respiratory system can become depressed. Brain damage, breathing problems, and death can result from combining these medications.