Antipsychotic + hyperthermia + lead-pipe rigidity + ↑CK + ΔMS
ABCDE
Stop causative drug; ABC; active cooling + fluids; dantrolene/bromocriptine; monitor for AKI.
First: Stop the antipsychotic
Treat: Cooling + IV fluids + Dantrolene / Bromocriptine
Order set
- Stop causative drug
- CK, U&E, VBG
- Active cooling + IV fluids
- Dantrolene/bromocriptine
- Monitor for AKI
Escalate / ICU
- Hyperthermia >40°C
- Rhabdomyolysis / AKI
- Autonomic instability
Criteria
AdmitAll NMS
ICUHyperthermia >40°C, rhabdomyolysis, autonomic instability
DialysisRefractory AKI from rhabdomyolysis
DischargeTemperature/CK normalised, renal stable, drug reviewed (no abrupt rechallenge)
Key
- Serotonin syndrome differs (clonus, hyperreflexia) → cyproheptadine. Active cooling including cooled IV fluids is appropriate in severe hyperthermia (>40 °C with organ dysfunction); avoid shivering (benzodiazepines) — iced fluids are only discouraged as sole therapy in mild cases.
Clinical detail — differentials, red flags, pitfalls, disposition
Red flags
- Hyperthermia >40°C
- Rhabdomyolysis/AKI
- Autonomic instability
Differentials
- Serotonin syndrome
- Malignant hyperthermia
- Sepsis
- Heat stroke
Common mistakes
- Withholding active cooling — cooled IV fluids are appropriate in severe hyperthermia
- Confusing with serotonin syndrome (clonus)
- Rechallenging too early — wait ≥2 weeks after full resolution, lowest potency, different agent, psychiatry-led
Disposition & follow-up
ICU supportive care; do not rechallenge abruptly.
Discharge package
MedicationsDo not restart the same agent abruptly; psychiatry-guided
Follow-upPsychiatry; monitor renal recovery
Warning symptomsFever, rigidity, confusion recurrence
💊 Treatment detail — doses & preparation
DantroleneNMS/malignant hyperthermia
Dose1–2.5 mg/kg IV bolus, repeat q5–10 min to max 10 mg/kg, then 1 mg/kg q6h ×24–48 h
Preparation20 mg vial reconstitute with 60 mL sterile water (slow to dissolve — warm, shake)
MonitorLFTs, muscle weakness; combine with aggressive cooling
Bromocriptinedopamine agonist
Dose2.5–5 mg PO/NG q8h (adjunct to stopping agent + cooling)
Preparation2.5 mg tablets crushed for NG
MonitorCK, renal function, rigidity trend
Lorazepambenzodiazepine
DoseStatus: 0.1 mg/kg IV (max 4 mg/dose), may repeat ×1
Preparation4 mg/mL vial dilute 1:1 with NS; slow push
MonitorRR, SpO₂; flumazenil caution in chronic users
📖 expert consensus / toxicologyReviewed July 2026