SAQ 143 – Toxicology – serotonin syndrome
Model Answer
Question 4. serotonin syndrome.
a. Cardinal features
- Alteration in behaviour or cognition.
- Autonomic nervous system overactivity such as sweating, rigors, diarrhoea, or cardiovascular instability.
- Neuromuscular activity such as rigidity, hyperreflexia, jerks, myoclonus, or hyperthermia.
b. Agents
- Analgesics such as fentanyl, pethidine, or tramadol.
- Antidepressants such as TCAs.
- Lithium.
- MAOIs such as moclobemide or phenelzine.
- SSRIs such as citalopram, fluoxetine, paroxetine, or sertraline.
- SNRIs such as venlafaxine.
- Drugs of abuse such as amphetamines, ecstasy, or MDMA.
- Herbal agents such as St John's wort.
c. Management
| Management step | Justification |
|---|---|
| Withdraw inciting agent | Reduce ongoing morbidity. |
| IV fluids | Fluid balance monitoring and supportive care. |
| Benzodiazepines | Reduce muscle activity / rigidity and therefore temperature; reduce anxiety and agitation; treat seizures. |
| Neuromuscular paralysis | If hyperthermia is severe. |
| Serotonin antagonists such as cyproheptadine | For significantly altered mental state or haemodynamic instability; evidence is limited. |
| Disposition | Ward if mild; HDU / ICU for moderate to severe cases needing close physiological observation. |
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