Hey! Thanks for sharing your story. Codeine is one of the weaker opiods but can be very addictive when used for long periods of time or when taken more than prescribed. He’s still worth saving if that’s what you want to know. Unfortunately, if he’s prescribed for pain he will seek medication everytime to help.
What your witnessing when he goes all coocoo probably be l withdrawal symptoms when he doesn’t have enough or if he misses a dose. They can affect people differently depending on how their bodies accept the drug. He will have to want to come off them completely or ask for alternative pain relief.
Good luck and stay strong!!
Link should help explain.
https://www.nhs.uk/medicines/dihydrocodeine/#:~:text=Dihydrocodeine%20is%20an%20opiate%20painkiller,is%20only%20available%20on%20prescription.