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Low Molecular Weight Heparin (LMWH) — VTE Prophylaxis Pregnancy: Compatible — LMWH does not cross placenta; see separate enoxaparin_pregnancy entry

Enoxaparin (VTE Prophylaxis — Post-Surgery)

Brand names: Clexane

Adult dose

Dose: Standard VTE prophylaxis: 40 mg SC once daily. High-risk renal impairment (eGFR 15–30): 20 mg SC OD. High-risk surgical patient: 40 mg SC OD (commence 6–12h post-operatively or 10–12h pre-operatively)
Route: Subcutaneous injection
Frequency: Once daily
Max: 40 mg/day (standard prophylaxis)
NICE NG89: commence LMWH pre-operatively (10–12h before incision) or post-operatively (6–12h after closure) in high-risk surgical patients. Continue until patient is fully mobile or for 28 days after major pelvic/abdominal cancer surgery. Stop 12h before spinal/epidural; restart 4h after needle removal.

Paediatric dose

Dose: 0.5 mg/kg
Route: Subcutaneous
Frequency: Once daily (prophylaxis) or twice daily (treatment)
Max: 40 mg per prophylactic dose
Concentration: 100 mg/mL pre-filled syringe mg/ml
Children: 0.5 mg/kg SC OD (prophylaxis). Treatment: 1 mg/kg SC BD. Anti-Xa monitoring in neonates and infants.

Dose adjustments

Renal

eGFR 15–30: 20 mg OD. eGFR <15: use unfractionated heparin instead

Hepatic

No dose adjustment required

Paediatric weight-based calculator

Children: 0.5 mg/kg SC OD (prophylaxis). Treatment: 1 mg/kg SC BD. Anti-Xa monitoring in neonates and infants.

Clinical pearls

  • NICE NG89: enoxaparin is first-line LMWH for VTE prophylaxis in surgical patients — single daily SC injection is more convenient and safer than UFH TDS
  • Extended prophylaxis: continue enoxaparin for 28 days after major abdominal or pelvic cancer surgery (ENOXACAN II trial evidence)
  • Epidural/spinal timing: stop enoxaparin 12h before neuraxial anaesthesia; do not restart for at least 4h after needle/catheter removal
  • Bridging for warfarin patients: use enoxaparin 1 mg/kg BD SC (treatment dose) as bridging around surgery when warfarin stopped
  • Obese patients: weight-based dosing may be required for adequate prophylaxis (some centres use 60 mg OD for BMI >40)

Contraindications

  • Active major bleeding
  • HIT (use alternative anticoagulant)
  • Thrombocytopenia <50×10⁹/L
  • Within 4h of spinal/epidural needle or catheter removal

Side effects

  • Injection site bruising (very common)
  • Bleeding
  • HIT (0.1–1% — less common than UFH)
  • Osteoporosis (prolonged use >3 months)
  • Hyperkalaemia

Interactions

  • NSAIDs/aspirin — increased bleeding risk
  • Other anticoagulants — additive bleeding

Monitoring

  • Platelet count (baseline; day 5–7 for HIT)
  • Renal function (eGFR, especially elderly)
  • Signs of bleeding
  • Anti-Xa levels (if obese, renal impairment, or extremes of weight)

Reference: BNFc; BNF; NICE NG89 VTE Prevention in Hospitalised Patients; ENOXACAN II Trial; ASRA Guidelines. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

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