Side effects associated with methadone can include constipation, nausea, sedation, vertigo, and edema.
In the case of heroin, craving and relapse can occur weeks and months after withdrawal symptoms are long gone.
Methadone, along with single-ingredient and combination forms of oxycodone and hydrocodone, was one of the most frequently reported drugs in terms of nonmedical use in emergency room visits in 2009.
Opana dulls an individual's perception of pain, and at higher doses it can affect other systems such as those that control respiration and circulation.