Report hyperthermia (temperature over 38.5-40 C), severe rigidity, seizures, or unstable vitals immediately.
Before you read
Test yourself first: 5 questions
Question 1 of 5
A client is prescribed an MAOI. The nurse reviews the medication list for dangerous interactions. Which combination is contraindicated and could cause a hypertensive crisis or serotonin syndrome?
Answer: A. MAOIs must not be combined with sympathomimetics or serotonergic drugs. Combining an MAOI with an SSRI, certain decongestants (pseudoephedrine), meperidine, or other antidepressants can cause hypertensive crisis or serotonin syndrome. A washout period (often 14 days, or 5 weeks for fluoxetine) is required between an MAOI and an SSRI.
Question 2 of 5
A client is prescribed an MAOI. Concurrent use of which drug class poses the greatest risk for serotonin syndrome and is contraindicated?
Answer: B. Combining an MAOI with an SSRI (or other serotonergic agents) can cause life-threatening serotonin syndrome. A washout period of about 2 weeks (5 weeks for fluoxetine) is required when switching between these drugs. The other classes do not carry the same risk.
Question 3 of 5
A client taking an SSRI for depression is also taking St. John's wort, an herbal supplement, for mood. Why is this combination a concern for the nurse?
Answer: A. St. John's wort has serotonergic activity. Combined with an SSRI or other serotonergic drugs, it increases the risk of serotonin syndrome. It also induces hepatic enzymes that can reduce levels of many other drugs. The client should be counseled to avoid combining it with prescribed antidepressants.
Question 4 of 5
A client taking fluoxetine is also given tramadol for pain. Two days later the client develops agitation, diaphoresis, hyperreflexia, tremor, and a temperature of 38.9 C (102 F). Which condition should the nurse suspect?
Answer: B. Combining serotonergic drugs such as an SSRI (fluoxetine) with tramadol can cause serotonin syndrome. Classic features are mental status changes (agitation), autonomic instability (diaphoresis, fever, tachycardia), and neuromuscular hyperactivity (hyperreflexia, tremor, clonus). The offending agents must be stopped.
Question 5 of 5
A client taking sertraline is also given a triptan for migraines and reports agitation, diaphoresis, tremor, hyperreflexia, and a temperature of 39.4 C (103 F). The nurse suspects which condition?
Answer: B. Serotonin syndrome results from excess serotonergic activity, often when an SSRI is combined with another serotonergic drug such as a triptan or MAOI. Signs include agitation, hyperthermia, diaphoresis, tremor, hyperreflexia, and clonus. It is a medical emergency requiring drug discontinuation.
Keep the streak going with more questions like these, each with a full rationale.
What is serotonin syndrome?
John's wort, linezolid) or a dose increase. It comes on rapidly, within hours, and is recognized by the triad of mental status changes, autonomic instability, and neuromuscular hyperactivity. Hyperthermia, agitation, hyperreflexia, and clonus are hallmark findings.
Key points to remember
- Onset is rapid (often within 6-24 hours of starting or increasing a serotonergic agent or adding a second one).
- Classic triad: altered mental status (agitation, confusion), autonomic instability (hyperthermia, tachycardia, hypertension, diaphoresis, dilated pupils), and neuromuscular hyperactivity (tremor, hyperreflexia, myoclonus, clonus, rigidity).
- A washout period is needed between an MAOI and an SSRI (typically about 2 weeks, longer for fluoxetine) to prevent the syndrome.
- Management includes stopping all serotonergic drugs, supportive care, cooling, benzodiazepines, and cyproheptadine as an antidote.
- Distinguished from NMS by rapid onset, hyperreflexia/clonus, and GI symptoms, whereas NMS is slow with rigidity and hyporeflexia.
Common causes
- SSRI + MAOI / triptan / tramadol
- St. John's wort, linezolid combos
- Onset RAPID, within hours
Signs & symptoms
- Agitation, confusion, hyperthermia
- Hyperreflexia, CLONUS, tremor
- Diaphoresis, diarrhea, ↑HR/BP
Nursing priorities
- Stop all serotonergic medications immediately and notify the provider.
- Monitor airway, vital signs, temperature, and neuromuscular status continuously.
- Implement active cooling measures for hyperthermia and continuous cardiac monitoring.
- Administer ordered benzodiazepines for agitation and cyproheptadine as the antidote.
- Provide IV fluids and a calm, safe environment with seizure precautions.
Labs & values
Patient teaching
- Tell every prescriber about all your medications, supplements, and St. John's wort before starting an antidepressant.
- Report agitation, fever, sweating, muscle twitching, or a racing heart, especially after a dose change.
- Do not start a new serotonergic drug or triptan without checking for interactions.
Red flags: report now
- Report hyperthermia (temperature over 38.5-40 C), severe rigidity, seizures, or unstable vitals immediately.
- Never combine an MAOI with an SSRI/SNRI or skip the required washout period between them.
- Sudden agitation, clonus, and high fever after a dose change is an emergency, not anxiety.
References
Clinical references for this topic
