Tricyclic antidepressants (TCAs) are more likely to cause cardiovascular and neurological toxicity than compared to Selective Serotonin Reuptake Inhibitors (SSRIs).

In a prospective hospital-based cohort study, we addressed the question of severity and outcome of antidepressant self-poisonings in patients who attended the Loghman-Hakim Hospital Poison Center. The severity was judged by impairment of consciousness, the outcome criteria were the requirement of inpatient treatment and endotracheal intubation as well as mortality. The aim of the study was to find out if TCA intoxications require more therapeutic efforts than SSRI intoxications.

From 28 March to 20 May 20 2006, all patients presented to the Poison Center were documented using preformatted forms by three trained nurses blinded to any study hypotheses. From 3.578 intoxications, a number of 334 patients with antidepressant or lithium self-poisoning was identified (9.3% of all poisoning cases; 233 females, 101 males; median age 24 years, min 13, max 70).

As compared to SSRI single-substance intoxications (n=17), TCA single-substance intoxications (n=73) were associated with (1) a significantly lower level of consciousness (p=0.005); (2) a significantly higher admission frequency (80.8% vs. 35.3%; p<0.001) and (3) a higher intubation frequency (13.7% vs. 0%; p=ns). SSRI multiple-substance intoxications were associated with a significantly lower level of consciousness than SSRI single-substance intoxications (p=0.042), while there was no significant difference between TCA multiple- and single-substance intoxications.

This study suggests that an overdose with SSRIs results in a more favorable clinical outcome than an overdose with TCAs.