Methadone users in detox also find more luck in therapy because they dont have to deal with constant opioid cravings or the severity of acute withdrawal symptoms. Advantages of methadone include:

Reduction in infectious disease due to the cessation of opiate misuse, especially injection drug abuse
Reduction in illegal crime due to the cessation in illicit drug usage
Overall increase in quality of life
Improved social functioning
More attendance in alcohol therapy since withdrawal symptoms arent a diversionMethadone replacement therapy will also help people achieve stabilization early on in their rehabilitation. People should devote 100% of their time to recovery, helping them to solve the underlying problems that lead to their opiate addiction. They will get a career and start to find a better balance in their lives. It also enables parents to continue raising their children in a safe home environment. When their conditions improve and they want to refrain from taking methadone, they must be properly weaned off the medication, which must be done under medical observation. Although other medication-assisted therapies for opiate addiction, such as buprenorphine, are available, methadone is often seen as the most promising alternative for people who are heavily addicted to opiates. Methadone has a number of serious side effects, including:

Slowed breathing
Sexual dysfunction
Nausea
Vomiting
Restlessness
Itchy eyesDosages can be adjusted after 1–2 days, or another medication may be recommended for your situation if you experience side effects. Lung and breathing complications are possible long-term side effects of methadone use. Methadone, as an opiate, has the potential to be addictive.
Though treatment reduces mortality rates, the period during the first four weeks after treatment begins and the four weeks after treatment ceases are the times that carry the highest risk for drug-related deaths. These periods of increased vulnerability are significant because many of those in treatment leave programs during these critical periods. Medications
Opioid replacement therapy (ORT) involves replacing an opioid, such as heroin, with a longer acting but less euphoric opioid. Commonly used drugs for ORT are methadone or buprenorphine which are taken under medical supervision. As of 2018, buprenorphine/naloxone is preferentially recommended, as the addition of the opioid antagonist naloxone is believed to reduce the risk of abuse via injection or insufflation without causing impairment.The driving principle behind ORT is the programs capacity to facilitate a resumption of stability in the users life, while the patient experiences reduced symptoms of drug withdrawal and less intense drug cravings; a strong euphoric effect is not experienced as a result of the treatment drug. In some countries (not the US, or Australia), regulations enforce a limited time for people on ORT programs that conclude when a stable economic and psychosocial situation is achieved. (People with HIV/AIDS or hepatitis C are usually excluded from this requirement.) In practice, 40–65% of patients maintain abstinence from additional opioids while receiving opioid replacement therapy and 70–95% can reduce their use significantly.