SURE!
yes
yes yes
when it contains marijuana, its never "safe"
You can if you have a prescription for the codeine. Remember that your ADHD makes you more likely to become addicted to things, so be careful with the codeine. Follow the doctor's directions carefully and don't take extra. Remember that codeine makes you drowsy and sluggish, also.
You could but it's advisable not to. Both are sedatives. Codeine is an analgesic anti-inflammatory. Xanax is a Benzodiazipine used in treating Anxiety disorders.
Because you could die and you never mix medicine with alchol
its probably that you have built up resistance to codeine if you take it regularly
Yes. However, citalopram will pretty much negate the effects of the codeine, and vice versa.Citalopram is CYP2D6 inhibitor, while codeine is a substrate.So you wont feel the codeine, or the citalopram.So I'd not do the codeine. You could try it though, if its not dangerous for you to not be on the citalopram.Ref http://en.wikipedia.org/wiki/Cyp2d6#CYP2D6_Ligands
Codeine on its own tastes extremely bitter. If you have to take it in a solution it's best to mix it with something sweet like fruit squash or kool-aid.
You can, but it's strongly encouraged to not mix the two unless necessary. Unless your doctor has told you to take them together for specific reasons, you shouldn't mix them.
Methadone is synthetic and quite harmful and highly addictive. Codeine and morphine are both natural - made from poppy extract. Of course, cyanide is also natural. 'Natural' does not mean 'safe'. Morphine is 10 times stronger than codeine. Morphine and methadone are highly addictive, while codeine only moderately.