Drug therapies for patients with substance use disorders are sometimes necessary or useful, but they are rarely sufficient to cure the disorder. If illicit drugs are overused by a patient with major depression to reduce psychic pain, by a patient with mania manifested as overactivity and uncontrolled hedonism, or by a patient with some other comorbid major Axis I disorder, appropriate drug therapy for the underlying major psychiatric condition can be very helpful. Unfortunately, some patients with clear syndromes (e.g., depression, bipolar disorder, schizophrenia) continue to abuse illicit drugs even when the syndromes are in full or partial remission, though others show improvement in both conditions with appropriate drug therapy.