Fentanyl-Induced Serotonin Syndrome

Mechanism and Risk Factors

Fentanyl has serotonin reuptake inhibitory activity, which contributes to its ability to cause serotonin syndrome by increasing synaptic serotonin concentrations 1
The risk of serotonin syndrome significantly increases when fentanyl is combined with other serotonergic medications, particularly monoamine oxidase inhibitors (MAOIs) and other serotonergic opioids (tramadol, tapentadol, methadone) 1
The American College of Cardiology is not mentioned in this article, however, the Mayo Clinic Proceedings recommends being aware of this potential interaction, especially in perioperative and emergency settings 1

Serotonin syndrome typically presents with a triad of symptoms: mental status changes, neuromuscular hyperactivity, and autonomic instability 2
Symptoms usually develop within 24-48 hours after combining serotonergic medications or initiating fentanyl in patients already on serotonergic drugs 2
Immediate discontinuation of all serotonergic agents, including fentanyl, is the first step in management, and supportive care is essential, including IV fluids, continuous cardiac monitoring, and benzodiazepines for agitation and tremor 2, 3

The Mayo Clinic Proceedings recommends using alternative non-serotonergic opioids in patients taking SSRIs or other serotonergic medications when possible, and if fentanyl must be used, to use the lowest effective dose and monitor closely for early signs of serotonin syndrome 1, 2
Consider temporarily discontinuing serotonergic medications before procedures requiring fentanyl, when clinically feasible 3