Serotonin syndrome can occur when multiple medications that alter serotonin metabolism are used.

Classically, this syndrome is produced when other serotonin-altering medications are used with MAOls.

This syndrome, which can be life-threatening, consists of symptoms outlined in Table 16-3. These include severe autonomic instability, motor abnormalities, and behavioral changes. The course of the disorder can become malignant and end in coma and death. A similar syndrome occurs when MAOls are used with meperidine or dextromethorophan, and perhaps other opiates.

Serotonin syndrome has many similarities to NMS but may be distinguished in the following ways. Serotonin syndrome does not produce muscular rigidity or dystonia as does NMS. Further, NMS occurs during the use of antipsychotic medication; while serotonin syndrome occurs through use of MAOls or other serotonergic agents.

Risk factors for serotonin syndrome, other than combining MAOls with other serotonin-altering medications, are not known.

Treatment for serotonin syndrome is largely supportive and may require intensive care with cardiac monitoring and mechanical ventilation. The offending medications should be discontinued.