Liverpool Hospital Emergency Department


  • Serotonin syndrome (mild to mod)
    • Antagonises – H1 and 5HT1+2 Receptors 
    • Not an antidote -> helps to alleviate symptoms 
  • Serotonin syndrome: CNS toxicity/ Autonomic features/ Neuromuscular  excitability.
  • Consider the use of oral benzodiazepines in cooperative patients with mild to  moderate agitation. 


  • Cyproheptadine 4mg tablets 

Dosage and Administration 

  • Adults:
    • For patients with significant agitation and sustained clonus use 12mg as a  single dose
    • Continue with 8mg PO / NG TDS for 24hrs until resolution of symptoms  o Paediatrics 
  •  <7 years of age 2mg as a single dose. 
  • >7 years of age  4mg as a single dose. 
  • Continued symptoms <7 years of age 2mg tds
  • >7 years of age 4mg tds  until symptom resolution 

Side Effects 

  • Anticholinergic properties but generally well tolerated 

Pit Falls 

  • Contraindicated in:
    • Acute asthma, closed angle glaucoma, bladder neck obstruction
    • Use alongside benzodiazepines & supportive care