The treating or evaluating clinician is usually able to get enough history from the person himself to make the diagnosis. Sometimes it is also helpful to talk to other people including family members as well. Any primary care physician or mental health clinician should be skilled in the detection and diagnosis of depression. It certainly is not always necessary to see a psychiatrist or psychologist if one believes they may be suffering from depression. It may also be helpful to see one's own primary care physician to make sure that there are nor other general medical factors that may be at play.
Depression is one of the most readily treatable medical illnesses.
There is some division of thought as to whether which of these treatments may be preferable. At any rate, it is clear that both psychotherapy or counseling and antidepressant medication can be very helpful for depression. Some depressions may respond very readily to one of the two treatments and others which may be more serious or complicated may require both. Antidepressant medications are generally prescribed by either primary care physicians or psychiatrists. The newer antidepressants which have become so much more readily popular generally have much more benign side effect profiles than the older antidepressants.