Core52: Drug-induced adverse reaction: serotonin syndrome

🧠 High-yield / 要点：Serotonin syndrome is caused by excess serotonergic activity. Key triggers: SSRIs, MAO inhibitors, TCAs, combinations of serotonergic drugs, linezolid, dextromethorphan, tramadol.

Definition / 定義

• Serotonin syndrome / SS = drug-induced toxicity due to excessive serotonin activity.
• Often occurs after:
  • Starting a serotonergic drug.
  • Dose increase.
  • Combining serotonergic agents.

Inducing drugs / 原因薬

Drug group	Examples / notes
Antidepressants	SSRIs, MAO inhibitors, tricyclic antidepressants
Combination therapy	Multiple serotonergic antidepressants together
Antibiotic	Linezolid
Antitussive	Dextromethorphan
Analgesic	Tramadol

Clinical idea / 臨床的ポイント

• Think of serotonin syndrome when symptoms appear after adding or combining serotonergic drugs.
• High-yield association:
  • SSRI + MAOI.
  • SSRI/SNRI/TCA + tramadol.
  • Serotonergic antidepressant + linezolid.
  • Serotonergic drug + dextromethorphan.

Treatment / 治療

• Stop serotonergic drugs.
• Supportive/symptomatic treatment.
• Benzodiazepines for agitation/neuromuscular symptoms.
• 5-HT antagonists, especially cyproheptadine.
• Dantrolene was listed in the lecture, but key exam concept is to distinguish SS from NMS and remove the trigger.

Remember / 覚え方

• Serotonergic drugs + interaction = serotonin syndrome
• Linezolid, tramadol, dextromethorphan are high-yield hidden triggers
• Treatment: stop drugs + supportive care + benzodiazepines ± cyproheptadine