Must all mental health problems and addiction be treated together?

See below: Crisis situations need to be addressed first. Often, people use addictive behaviors to cope with stress, etc. Addictive behaviors and mental health problems feed onto each other (addictions might lead to more problems, while more problems might exacerbate addictions). There's no cookbook and every person is different. A therapist will meet you at whatever level you're at to help you.

Better together: Boils down to it is real hard to fix one, without fixing the other. Addiction is a mental disorder. Many, if not nearly all, psychological symptoms can get worse with recreational drug use. It is not effective to spend time and money on treatment of one while ignoring the other. They are tightly connected through the one and only brain you have. Treating them together makes the most sense.