Methadone interacts with a meaningful number of other medications — telling every provider and pharmacist about your methadone treatment is one of the simplest ways to prevent a problem.
CYP3A4 and related liver enzymes: Methadone is metabolized by liver enzymes that many other medications affect. Strong inducers (some anti-seizure medications, some HIV medications, St. John’s Wort) can lower methadone levels, potentially causing withdrawal; strong inhibitors can raise levels, increasing overdose and QT-prolongation risk.
Other QT-prolonging medications: Certain antibiotics, antidepressants, and antipsychotics also prolong the QT interval — combining these with methadone compounds that specific cardiac risk. QT prolongation article
Sedating medications: Combining methadone with benzodiazepines, alcohol, or other sedatives significantly increases overdose risk through combined respiratory depression — this is a serious concern, not a minor caution.
What to always do: Bring a complete, current medication list — including over-the-counter drugs and supplements — to every OTP visit, and tell any new prescriber (including dentists and specialists) that you’re on methadone.
Medically reviewed by [pending]. Sources: SAMHSA TIP 63, FDA prescribing information.