Patient handout

Serotonin syndrome

PRODUCTION

1. Your condition

This handout is for serotonin syndrome. Your care team identified this based on: recent serotonergic dose change/addition + clonus / hyperreflexia / myoclonus / tremor (serotonin toxicity cluster) [boyer & shannon nejm 2005].

Other reasons your team may use this plan: core temperature >38.5°c with inducible/spontaneous clonus or hypertonia after a serotonergic agent (severe serotonin toxicity) [hunter criteria — dunkley qjm 2003]; agitation / anxiety / confusion + autonomic instability (tachycardia, diaphoresis, mydriasis) within 24h of a serotonergic medication [boyer & shannon nejm 2005]; serotonergic drug interaction (ssri/snri + maoi, linezolid + ssri, maoi + meperidine/tramadol) or serotonergic overdose [acmt serotonin toxicity guidance].

2. Your medications

Take these medications exactly as prescribed. Do not stop or change a dose without talking to your provider.

Medication	Starting dose	How	When	What it does
discontinue_all_serotonergic_agents	Immediately stop SSRI/SNRI, MAOI (incl linezolid, methylene blue), TCA, triptans, tramadol/meperidine/fentanyl, dextromethorphan, ondansetron, lithium, MDMA/amphetamines, St John’s wort	medication_discontinuation	once, sustained	Boyer & Shannon NEJM 2005 — removing the offending serotonergic agent is the single most important intervention; most cases resolve within 24h after removal + supportive care
isotonic_crystalloid	Balanced crystalloid / NS — resuscitate then target generous UOP titrated to CK trend and volume status	IV	bolus + maintenance titrated	ACMT — IV fluids + brisk urine output support cooling and rhabdomyolysis/AKI prevention; core supportive measure alongside continuous monitoring

Plan: Serotonin syndrome — STOP serotonergic agents → supportive + benzodiazepine sedation → active cooling for hyperthermia → cyproheptadine (moderate-severe) → SEVERE: deep sedation + non-depolarizing paralysis + intubation (definitive for hyperthermia/rigidity) → rhabdo/AKI management (Boyer & Shannon NEJM 2005; ACMT serotonin toxicity guidance)

4. When to seek emergency care

Call 911 or go to the nearest emergency room right away if you have:

Core temperature >38.5–41°C in a serotonergic-toxic patient (severe serotonin toxicity hyperthermia) [Boyer & Shannon NEJM 2005](life-threatening)
Severe (lower-limb-predominant) rigidity/hypertonia compromising ventilation or rapidly rising temperature [Boyer & Shannon NEJM 2005](life-threatening)
Seizure complicating serotonin toxicity [Boyer & Shannon NEJM 2005]
Markedly elevated CK with rising creatinine / myoglobinuric AKI, or disseminated intravascular coagulation [ACMT serotonin toxicity guidance]
Rapidly rising core temperature in serotonin toxicity even before the 38.5°C threshold (impending life-threatening hyperthermia) [Boyer & Shannon NEJM 2005]
Severe autonomic instability — labile/extreme hypertension or hypotension with tachycardia and diaphoresis in serotonin toxicity [Boyer & Shannon NEJM 2005]

5. Follow-up

Medication reconciliation to remove/avoid the offending serotonergic combination (durable allergy/interaction flag), pharmacist review of MAOI/linezolid/methylene-blue washout intervals, psychiatry safety plan if intentional, nephrology if AKI, return precautions for re-exposure [ACMT serotonin toxicity guidance]

6. Sources

Guideline: Hunter Serotonin Toxicity Criteria (Dunkley QJM 2003); Boyer & Shannon, The Serotonin Syndrome, NEJM 2005; 2024-2025 critical-care toxicology reviews of serotonin toxicity and ACMT serotonin toxicity guidance