Serotonin toxicity recognition and management (MEQ)

(i) Diagnosis and criteria. Working diagnosis: serotonin toxicity precipitated by phenelzine (MAOI) + tramadol. Apply Hunter Serotonin Toxicity Criteria: serotonergic agents present; inducible clonus + diaphoresis/agitation fulfils a diagnostic pathway (also tremor/hyperreflexia pathway). Onset within hours fits. No lab confirms the diagnosis.[1][3][4]

(ii) Immediate management. Stop phenelzine and all other serotonergic agents; do not give further tramadol. ABCDE support, continuous monitoring, IV fluids, active cooling for fever. Benzodiazepines for agitation/neuromuscular hyperactivity (e.g. lorazepam 1–2 mg IV, titrate carefully with airway vigilance). Give cyproheptadine 12 mg oral/NG loading dose, then 2 mg every 2 hours if symptoms continue; maintenance often 8 mg every 6 hours. Check ECG, U and E, CK. Escalate to ICU if rigidity/temperature worsen.[2][3][5]

(iii) Not NMS; avoid wrong drugs. NMS is linked to dopamine antagonists, slower onset (days–weeks), lead-pipe rigidity and bradyreflexia. This case has MAOI+tramadol, hours onset, hyperreflexia/clonus — serotonergic. Do not give bromocriptine/amantadine (may worsen serotonergic state). Do not continue the MAOI. Dantrolene is not first-line for SS.[2][6]

(iv) High-risk combinations. MAOI + SSRI/SNRI/SRI-active TCA; MAOI + pethidine/meperidine; MAOI + tramadol; MAOI + dextromethorphan; linezolid + antidepressant; methylene blue + antidepressant; multi-agent serotonergic stacks; MDMA contexts.[2][4]

(v) Disposition and restart. Admit (likely HDU/ward with continuous observation at minimum; ICU if progresses). After resolution, redesign antidepressant plan with appropriate washout before any future MAOI or high-risk combination; educate about OTC cough mixtures and pain medicines; toxicology/pharmacy involvement; psychiatric follow-up for depression.[3][5]