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Opioid Analgesic (Weak) / SNRI

Tramadol 50–100mg

Brand names: Zamadol, Zydol, Mabron (MR)

Adult dose

Dose: 50–100mg every 4–6h as required
Route: Oral, IM, or IV
Frequency: Every 4–6h PRN; modified release: 100–200mg BD
Max: 400mg/day (200mg/day in elderly or hepatic impairment)
Moderate-to-severe musculoskeletal pain (step 2–3 WHO ladder). Start 50mg QDS, titrate to response. MR formulation (Mabron, Zydol XL) for regular use. IV: 50–100mg slow IV over 2–3 min, max 600mg/day.

Paediatric dose

Dose: 1 mg/kg
Route: Oral or IV
Frequency: Every 4–6h
Max: 100mg per dose
Concentration: 50 mg/mL drops; 50 mg capsules mg/ml
Children >12 years only (UK licence). Not recommended <12 years — risk of respiratory depression (especially after tonsillectomy in ultra-rapid CYP2D6 metabolisers). 1–2 mg/kg per dose every 6h.

Dose adjustments

Renal

eGFR 10–30: extend interval to every 12h; avoid MR preparations. eGFR <10: avoid.

Hepatic

Max 200mg/day; avoid MR preparations in severe hepatic impairment

Paediatric weight-based calculator

Children >12 years only (UK licence). Not recommended <12 years — risk of respiratory depression (especially after tonsillectomy in ultra-rapid CYP2D6 metabolisers). 1–2 mg/kg per dose every 6h.

Clinical pearls

  • Dual mechanism: weak mu-opioid agonist + noradrenaline/serotonin reuptake inhibitor — different side effect profile to pure opioids
  • Serotonin syndrome risk: particularly when combined with SSRIs, tramadol common cause of ED presentations for serotonin toxicity — avoid combination where possible
  • CYP2D6 polymorphism: ultra-rapid metabolisers convert tramadol to morphine rapidly — increased toxicity risk; poor metabolisers have reduced efficacy
  • Start antiemetic prophylaxis (metoclopramide or domperidone) for first 2 weeks — nausea is the most common reason for discontinuation
  • Schedule 3 controlled drug in UK — prescription requirements apply

Contraindications

  • Concurrent or recent MAOI use (within 14 days — risk of serotonin syndrome)
  • Uncontrolled epilepsy (lowers seizure threshold)
  • Acute intoxication (alcohol, opioids, sedatives)
  • Children <12 years (UK licence)
  • Post-tonsillectomy/adenoidectomy pain in children (MHRA warning)

Side effects

  • Nausea and vomiting (very common — consider antiemetic prophylaxis)
  • Dizziness
  • Constipation
  • Drowsiness
  • Seizures (lowers threshold — particularly at high doses or in susceptible patients)
  • Serotonin syndrome (with SSRIs, SNRIs, MAOIs)
  • Dependence and withdrawal

Interactions

  • MAOIs — contraindicated; serotonin syndrome risk
  • SSRIs/SNRIs — serotonin syndrome risk (use with caution)
  • Carbamazepine — reduces tramadol levels and increases seizure risk
  • Warfarin — enhanced anticoagulant effect reported
  • CNS depressants — additive sedation

Monitoring

  • Pain scores
  • Nausea/vomiting
  • Signs of serotonin syndrome (agitation, hyperthermia, clonus, tachycardia)
  • Seizure risk assessment

Reference: BNFc; BNF; NICE NG59 (Low Back Pain); WHO Analgesic Ladder; MHRA Drug Safety Update (tramadol in children). Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

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