Low-molecular-weight heparin (LMWH)
ATC code: B01AB05 (Enoxaparin)
Brand names
Clexane, Lovenox, Enoxalem
A low-molecular-weight heparin with mean mass 4500 Da. Potentiates antithrombin III and inactivates factor Xa and, to a lesser extent, thrombin (factor IIa); anti-Xa/anti-IIa ratio is about 3.8:1. Predictable action without routine coagulation monitoring. Subcutaneous bioavailability 92%; half-life 4–5 hours. Renal elimination – adjust dose in severe renal impairment.
First line
In acute deep vein thrombosis and pulmonary embolism, LMWHs are first-line initial anticoagulation with transition to oral anticoagulants (DOACs or warfarin) after 5–10 days. Dose 1 mg/kg subcutaneously twice daily or 1.5 mg/kg once daily. In cancer-associated venous thromboembolism, enoxaparin remains the preferred long-term option for the first 6 months per ASCO 2023.
First line
First-line for venous thromboembolism prophylaxis after major surgery and in hospitalized acutely ill medical patients per ACCP 2021 and 2024. Standard dose: 40 mg subcutaneously once daily in general surgery; 30 mg twice daily or 40 mg once daily in orthopedic surgery. Duration: 7–10 days in general surgery, up to 35 days after major orthopedic procedures (hip and knee replacement, hip fracture).
The drug is promoted for these uses outside international guidelines. Each entry below is analyzed against AEMPS, FDA, EMA, Cochrane and major RCTs.
Not recommended
Enoxaparin is a low-molecular-weight heparin. It is used for prevention and treatment of venous thromboembolism, for acute coronary syndrome, and during surgery with high thrombotic risk (ACCP 2024, 2023). In anti-aging regimens, enoxaparin is used for blood thinning in people without confirmed thrombotic risk. In healthy adults, no clinical studies of prophylactic use exist. The drug raises the risk of major bleeding and heparin-induced thrombocytopenia (HIT, which can cause paradoxical thrombosis) and requires subcutaneous injection. If enoxaparin was prescribed for blood thinning in a healthy person, consider seeking a second opinion.
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Boxed warning
FDA boxed warning: epidural or spinal hematomas with paralysis risk in patients receiving LMWH around neuraxial anesthesia or spinal puncture. Respect dosing intervals between LMWH and the procedure.
FDA category B. Does not cross the placenta. Drug of choice for anticoagulation in pregnancy (thrombophilia, mechanical valve, VTE prevention) – unlike warfarin and DOACs. Dose by body weight with optional anti-Xa monitoring in T3.
Compatible with breastfeeding. Enoxaparin essentially does not pass into milk and is not absorbed from the infant GI tract.
Reference information, not a clinical decision. Discuss feeding pauses or changes with your physician or an IBCLC.
Enoxaparin sodium is evaluated for the following indications with varying evidence strength: Venous thromboembolism prophylaxis (evidence tier A), Venous thromboembolism (evidence tier A), Anti-aging and longevity (evidence tier F). See the full indication matrix with dosing and citations above on this page.
Common side effects of Enoxaparin sodium (≥ 1 in 100): Injection site hematoma and pain, Minor bleeding, Transient thrombocytopenia, Elevated liver enzymes. See the Safety section for uncommon and serious reactions.
FDA category B. FDA category B. Does not cross the placenta. Drug of choice for anticoagulation in pregnancy (thrombophilia, mechanical valve, VTE prevention) – unlike warfarin and DOACs. Dose by body weight with optional anti-Xa monitoring in T3.
Compatible with breastfeeding. Enoxaparin essentially does not pass into milk and is not absorbed from the infant GI tract.
Enoxaparin sodium is contraindicated in: Enoxaparin or heparin hypersensitivity; Active clinically significant bleeding; History of heparin-induced thrombocytopenia; Platelet count under 50×10⁹/L; Severe uncontrolled hypertension. Full list in the Safety section.
FDA boxed warning: epidural or spinal hematomas with paralysis risk in patients receiving LMWH around neuraxial anesthesia or spinal puncture. Respect dosing intervals between LMWH and the procedure.