I was put on methdone in 2011 along with hydrocodone after trying a lot of other medications. The side affects were all bad for me so I ended up on methdone and hydrocodone.   I stopped hydrocodone several years ago because it causes frustration.   I stayed on methdone for the pain.  Methadone is now causing headaches for the past year before that it was just chronic fatigue.  Now it's chronic fatigue and headaches.  