A 32-year-old woman on sertraline 100 mg daily for depression is started on tramadol 50 mg TDS for chronic back pain by an orthopaedic surgeon unaware of her psychiatric medication. Within 48 hours, she develops tremor, hyperreflexia, clonus, agitation, and a core temperature of 38.5°C. She is brought to the emergency department. What is the most appropriate immediate next step in management?

Explanation

## Clinical Diagnosis: Serotonin Syndrome **Key Point:** This patient presents with the classic triad of serotonin syndrome: **autonomic instability** (fever 38.5°C), **neuromuscular hyperactivity** (tremor, hyperreflexia, clonus), and **altered mental status** (agitation). The combination of sertraline (SSRI) + tramadol (weak SNRI + opioid with serotonergic activity) is a well-recognized high-risk combination. ## Management Algorithm ```mermaid flowchart TD A[Suspected Serotonin Syndrome]:::outcome --> B{Severity?}:::decision B -->|Mild-Moderate| C[Discontinue offending agent<br/>Supportive care<br/>Benzodiazepines PRN]:::action B -->|Severe<br/>High fever/Altered MS| D[IMMEDIATE discontinuation<br/>of ALL serotonergic drugs]:::urgent D --> E[Active cooling measures]:::action D --> F[IV fluids & monitoring]:::action D --> G[ICU admission if needed]:::action E --> H[Cyproheptadine if severe]:::action F --> I[Monitor CK, renal function<br/>Watch for rhabdomyolysis]:::action ``` ## Why Immediate Discontinuation? **High-Yield:** Serotonin syndrome is a **dose-dependent, drug-interaction phenomenon**. Unlike neuroleptic malignant syndrome (NMS), which requires days to develop and resolve, serotonin syndrome: - Develops **within hours to days** of dose increase or drug combination - **Resolves within 24–72 hours** of drug discontinuation - Does NOT require antipsychotic re-challenge to diagnose - **Worsens if serotonergic drugs are continued** **Clinical Pearl:** The presence of **clonus** (spontaneous or inducible) is the most specific sign of serotonin syndrome and should trigger immediate cessation of serotonergic agents. ## Supportive Care Essentials 1. **Discontinue both sertraline and tramadol immediately** — no taper needed in acute setting 2. **Active cooling** — ice packs, cooling blankets, IV cold saline if core temp > 39°C 3. **Benzodiazepines** (lorazepam 2–4 mg IV/IM) for agitation and muscle rigidity 4. **IV hydration** to prevent acute kidney injury and rhabdomyolysis 5. **Monitor CK, creatinine, electrolytes** — risk of myoglobinuria 6. **Cyproheptadine** (non-selective 5-HT antagonist) 12 mg loading dose, then 2 mg Q2H (max 32 mg/day) — reserved for **severe cases with high fever or altered consciousness** **Warning:** Do NOT continue either drug hoping benzodiazepines alone will control symptoms — the underlying serotonergic excess must be removed. [cite:Harrison 21e Ch 397]