According to recent epidemiological studies, the lifetime prevalence of major depression ranges between 10 and 20%. However, informations concerning the course of depressive illness remain limited. It appears that only about one-quarter, or even less, of all depressives are affected once in their lifetime. Today, it could be assumed that 75-80% of depressive cases are recurrent. Many antidepressive treatments are available today, including first generation and second-generation antidepressants, psychotherapies, and sismotherapies. While antidepressants are similar in terms of drug or efficacy, onset of action, and latency to treatment response, their potential side effect and toxicity profiles are quite different. These factors must be weighed before treatment of depression is begun in an effort to prescribe the compound that is most beneficial i.e., clinically effective while exhibiting the fewest negative aspects. Determination of patients with an "at-risk" profile for drug side effects is best done by a careful analysis of their medical history, comorbidity with other axis I and axis II disorders and concomitant drug therapies. In fact, it appears that depressive patients with coexisting anxiety are often prone to side effects either with tricyclic compounds and SSRI's. In these patients these medications should therefore be introduced at a low dose and slowly increased. Otherwise, because of the frequent comorbidity of depression and alcoholic disorders, the clinician should make very effort to obtain a detailed history of the patient's substance use. If the patient is found to have a substance use disorder, a program to secure abstinence should be regarded as a priority in the treatment.(ABSTRACT TRUNCATED AT 250 WORDS)