As long as you don't abuse the benzodiazepine then you'll be fine.It's when you mix a benzo with opiate pain killers or alchohol that you can have respitory failure.I've been on methadone for 4 years now and every time we hear of a death of a methadone patient from an od, it almost always comes out that they were abusing valium or xanax ect.Methadone and benzo's are a lethal mixture if not taken properly.So be very careful because this usually happens when you're asleep.Take care......Dave:)