Side effects remain one of the most important clinical issues in antidepressant therapy. Patients may not be able to take appropriate treatment or may not tolerate their medication in adequate doses or for an adequate length of time to manage their depressive illness. This article reviews the extensive safety data from 6705 patients treated with paroxetine. These data indicate that paroxetine has no significant cardiovascular effects, few significant drug interactions, and no clinically significant effects on the ECG or EEG. Furthermore, paroxetine is relatively safe in overdose and has very little anticholinergic activity. Psychomotor performance is not impaired by paroxetine and there is no evidence of any zimelidine-like hypersensitivity reactions or increase in suicidal ideation. As with other selective serotonin reuptake inhibitors (SSRIs), the most common side effect is gastrointestinal upset, especially nausea. This is usually very well tolerated and rarely leads to drug discontinuation. As with other SSRIs, monoamine oxidase inhibitors should not be prescribed concurrently or soon after discontinuing paroxetine because of the risk of a lethal interaction. Paroxetine may be less likely than currently available SSRIs to cause agitation. In general, paroxetine has a very favorable side effect profile and should be an important alternative in the medical treatment of depressive illness.