What is Doxepin primarily used to treat?

Doxepin is primarily used to treat depression, which positions it as a tricyclic antidepressant. This medication works by influencing neurotransmitters in the brain, specifically norepinephrine and serotonin, which play critical roles in mood regulation.

While Doxepin can also have off-label uses, such as for anxiety or insomnia, its main indication remains the treatment of depressive disorders. The emphasis on its primary use as an antidepressant highlights its role in alleviating the symptoms of depression, making it a crucial option for individuals diagnosed with this condition.

In the context of the other conditions listed, anxiety might be treated with Doxepin but not as its primary indication; schizophrenia is typically managed with antipsychotics, and attention deficit hyperactivity disorder (ADHD) is generally treated with stimulants or other specific medications designed for that condition. Hence, its primary classification and usage in the treatment of depression are what affirm the correctness of selecting that option.