Background: The morbidity and mortality caused by tricyclic antidepressant (TCA) overdose are well recognized. Among newer antidepressants, the selective serotonin reuptake inhibitors (SSRIs) are thought to be safer in overdose. This study was designed to describe the signs, symptoms, and mortality associated with SSRI overdose.
Method: English-language articles identified through MEDLINE (1985 through 1997), and case reports from the American Association of Poison Control Centers (AAPCC) (1987 through 1996) and United States Food and Drug Administration (FDA) adverse event database (through 1997) that describe findings of fatal and nonfatal overdoses involving SSRIs alone or in combination with other ingestants were reviewed.
Results: SSRI antidepressants are rarely fatal in overdose when taken alone. During the 10 years that SSRI antidepressants have been marketed, there have been remarkably few fatal overdoses reported in the literature or to the AAPCC or FDA involving ingestion only of an SSRI. Moderate overdoses (up to 30 times the common daily dose) are associated with minor or no symptoms, while ingestions of greater amounts typically result in drowsiness, tremor, nausea, and vomiting. At very high doses (> 75 times the common daily dose), more serious adverse events, including seizures, electrocardiogram (ECG) changes, and decreased consciousness may occur. SSRI overdoses in combination with alcohol or other drugs are associated with increased toxicity, and almost all fatalities involving SSRIs have involved coingestion of other substances.
Conclusion: The SSRI antidepressants are far safer than the TCAs in overdose. There is no apparent difference among SSRIs with respect to overdose safety.