I can tell you this much from personal experience. Those attacks @Wayover mentioned are NO JOKE!! OMG they are terrible. Its one of the worst, most uncontrollable pains i've ever dealt with. Thank god for @Wayover or else i wouldnt have had a clue what i was experiencing when i had one of those attacks. It hurts so bad it will drop you to your knees in agony and all you can do is PRAY that god relieve you from the pain you are in. And there is NO way too describe this particular pain. Only thing i can say about it is, it F'n HURTS!!!!
Anyways, chocolate is a big time creator of this pain. Speaking for me personally, yes, chocolate does interact with methadone. BUT, im not talkin about a few chocolate candy bars throughout the day. If you over do it and eat too much chocolate, it IMO, most definitely has the tendency too react with the methadone. That's just my own personal experience. Everybody's body is different. Im also not a doctor or medical professional therefore im only giving you my own personal experiences. Hope this helps.