Main methadone side effects

Common opioids side effects:

  • Constipation,

  • Nausea, vomiting,

  • Urinary retention (rarely at a distance from initiation),

  • Myoclonus,

  • Respiratory depression,

  • Sedation,

  • Cognitive impairment (including hallucinations, nightmares, agitation)

Methadone specific side effect:

  • QT prolongation with risk of torsade de pointes for high doses (>120mg/day). Caution for drug interaction with risk of QT allongement.