What drugs can interact with methadone? from Jennifer Lorax's blog

You may have breathing issues or withdrawal symptomsif you start or stop taking certain other drugs. Tell your doctor if you also use antibiotics, antifungal medication, heart or blood pressure medication, seizure medication, or medicine to treat HIV or hepatitis C.

Opioids can interact with many other medicines and cause dangerous side effectsor death. Make sure to tell your doctor if you also use:

• other narcotic medication - opioid pain medicineor prescription cough medicine

• sedatives like Valium, including diazepam, alprazolam, lorazepam, Ativan, Klonopin, Restoril, Tranxene, Versed, Xanax, and others

• drugs that make you sleepy or slow your breathing - a sleeping pill, muscle relaxer, tranquilizer, antidepressant, or antipsychotic medicine

• drugs that affect levels of serotonin in your body - a stimulant or medicine for depression, Parkinson’s disease, migraine headaches, serious infections, or prevention of nausea and vomiting