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SARI (Serotonin Antagonist and Reuptake Inhibitor) Pregnancy: Avoid if possible — limited data. Use sertraline in preference.

Trazodone

Brand names: Molipaxin

Adult dose

Dose: Depression with anxiety or insomnia: 150mg OD at night initially (or 50mg TDS); increase by 50mg every 3–4 days; usual effective dose 150–300mg OD. Maximum 600mg daily (hospitalised patients under specialist care).
Route: Oral
Frequency: Once daily at night (preferred) or divided doses
Max: 600mg daily (inpatient specialist setting); 300mg OD (outpatients)
Mechanism: 5-HT2A receptor antagonist AND serotonin reuptake inhibitor. Useful when sedation is a therapeutic goal (insomnia with depression). Lower anticholinergic burden than TCAs. Associated with priapism (rare but serious — urological emergency). Often used at sub-antidepressant doses (50–100mg ON) specifically as a non-addictive sleep aid in depression.

Paediatric dose

Route: Oral
Frequency: Once daily at night
Max: Not applicable
Not licensed under 18 years. Seek specialist child and adolescent psychiatry opinion.

Dose adjustments

Renal

Use with caution in severe renal impairment — limited data.

Hepatic

Reduce dose in hepatic impairment — hepatic metabolism.

Clinical pearls

  • Priapism: advise male patients at initiation — rare (1:6000) but can cause permanent erectile dysfunction if not treated promptly (aspiration, alpha-agonist injection). Advise patient to attend ED immediately for erection lasting >4 hours
  • Sub-antidepressant use for insomnia: 50–100mg ON is widely used as a non-addictive sleep aid — not a scheduled/controlled drug unlike zopiclone or benzodiazepines
  • Orthostatic hypotension: particularly problematic in the elderly — check standing BP; start low (50mg)
  • No anticholinergic activity — safer in elderly than TCAs, BPH patients

Contraindications

  • MAOIs within 14 days
  • Hypersensitivity to trazodone
  • Acute intoxication with alcohol or CNS depressants

Side effects

  • Sedation (therapeutically useful)
  • Orthostatic hypotension (alpha-1 blockade)
  • Dizziness, headache
  • Nausea
  • Dry mouth (minimal anticholinergic effect)
  • Priapism (rare but urological emergency — advise patient to seek emergency care immediately)
  • QTc prolongation (at higher doses)

Interactions

  • MAOIs — contraindicated (serotonin syndrome)
  • CNS depressants, alcohol — additive sedation
  • CYP3A4 inhibitors (ketoconazole, ritonavir) — increase trazodone levels; reduce dose
  • Digoxin, phenytoin — trazodone may increase levels

Monitoring

  • Blood pressure (orthostatic — sit to stand)
  • Mood and sleep response
  • Priapism awareness counselling (men)

Reference: BNFc; BNF 90; NICE CG90 (Depression). Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

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