04/02/2026
тЭЗя╕П Serotonin Syndrome тАФ Rapid Review
тЖТ Definition: Life-threatening toxicity from excess serotonin (5-HT1A/5-HT2A overstimulation)
тЖТ Onset: Rapid (within hours of drug exposure or dose increase)
Common Causes
тЖТ SSRIs/SNRIs
тЖТ MAOIs (highest risk when combined with SSRIs)
тЖТ TCAs
тЖТ Triptans
тЖТ M**A, co***ne, amphetamines
тЖТ Tramadol, dextromethorphan, lithium, St JohnтАЩs wort
Classic Triad
тЖТ Mental status: agitation, confusion, delirium
тЖТ Autonomic: hyperthermia, diaphoresis, tachycardia, hypertension, diarrhea
тЖТ Neuromuscular: hyperreflexia (LL > UL), clonus, tremor, rigidity
Mnemonic: SHIVERS
тЖТ Shivering
тЖТ Hyperreflexia
тЖТ Increased temperature
тЖТ Vitals unstable
тЖТ Encephalopathy
тЖТ Restlessness
тЖТ Sweating
Key Diagnostic Clue
тЖТ Recent serotonergic drug + clonus + hyperreflexia
тЖТ Diagnosis is clinical
Differentiate from NMS
тЖТ Serotonin syndrome: fast onset, clonus, hyperreflexia, dilated pupils
тЖТ NMS: slow onset, lead-pipe rigidity, normal pupils
тЖТ Treatment: Cyproheptadine vs Dantrolene
Management
тЖТ Stop offending drugs
тЖТ IV fluids + monitoring
тЖТ Benzodiazepines
тЖТ Cyproheptadine (moderateтАУsevere)
тЖТ Severe hyperthermia тЖТ intubation + active cooling
тЖТ Antipyretics ineffective
Complications
тЖТ Rhabdomyolysis
тЖТ AKI
тЖТ Metabolic acidosis
тЖТ DIC
тЖТ Death
Exam Pearls
тЖТ Rapid onset = serotonin syndrome
тЖТ Hallmark = clonus + hyperreflexia
тЖТ Most dangerous combo = SSRI + MAOI
тЖТ Antidote = Cyproheptadine
Medical Point