About methadone
Synthetic opioid analgesic
Used for
- Severe pain when other treatments are unsuitable
- Opioid dependence treatment in specialist programs
Usual adult dose
Pain: individualized, often 2.5–10 mg by injection every 8–12 hours. Dependence: oral dosing is usual; specialist-supervised and individualized.
Usual dose in children
Not routinely used for children; specialist dosing is required.
Common side effects
- Sleepiness, dizziness, nausea, and vomiting
- Constipation and sweating
- Slow or shallow breathing
- Abnormal heart rhythm, including QT prolongation
Important warnings
- Can cause fatal breathing suppression, especially when starting or increasing doses.
- Dependence and withdrawal can occur; overdose risk rises when tolerance falls.
- Avoid alcohol and other sedatives unless specifically supervised.
- Can prolong the QT interval and cause dangerous heart rhythms.
Pregnancy
May be used for opioid dependence under specialist care; prolonged use can cause newborn withdrawal. Pain treatment requires careful assessment.
Breastfeeding
Methadone can pass into breast milk. Use requires clinical supervision; monitor the infant for unusual sleepiness or breathing problems.
Interactions
- Alcohol, benzodiazepines, and other sedatives increase breathing suppression.
- Medicines affecting methadone breakdown can change its effects or cause withdrawal.
- Some medicines increase QT prolongation and dangerous rhythm risk.
- Serotonergic medicines may increase the risk of serotonin syndrome.
AI-generated from general medical knowledge, not from this product's official leaflet. It may be incomplete or out of date. Not medical advice — ask a pharmacist or doctor before making any decision.