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Enoxaparin: 7 things you should know

Medically reviewed by Carmen Fookes, BPharm. Last updated on Dec 30, 2022.

1. How it works

  • Enoxaparin may be used to reduce the risk of blood clots or for the treatment of unstable angina or a heart attack.
  • Enoxaparin works by binding to and accelerating the activity of antithrombin III, a substance that inhibits the activity of certain clotting factors, specifically Xa and IIa, that are involved in the formation of blood clots. Thrombin production is decreased which prevents fibrin clot formation. Blood remains free-flowing and less likely to clot.
  • Enoxaparin belongs to the class of medicines known as low molecular weight heparins (LMWH). It may also be called an anticoagulant.

2. Upsides

  • Used to reduce the risk of further blood clots that may lead to pulmonary emboli (blood clots in the lungs) in people with acute deep vein thrombosis (DVT) (a blood clot in the deep veins of the legs).
  • Used to protect against the development of DVT in people undergoing abdominal surgery, hip or knee replacement surgery, or with severely restricted mobility.
  • May also be used in the treatment of unstable angina and myocardial infarction (a heart attack).
  • Routine blood tests such as Prothrombin time (PT) or Activated Partial Thromboplastin Time (aPTT) are relatively insensitive measures of enoxaparin efficacy and are not required. However, periodic complete blood counts (including platelet counts) and occasional testing for blood in the feces may be recommended depending on the duration of therapy.
  • Dosage adjustment of enoxaparin is not required in mild-to-moderate renal impairment; however, anyone with renal impairment should be monitored for signs of excessive bleeding.
  • People requiring ongoing enoxaparin can be taught to self-inject it subcutaneously (under the skin) so that they can administer it themselves at home.
  • Brand names for enoxaparin injection include Lovenox and Clexane.
  • Generic enoxaparin injection is available.

3. Downsides

If you are between the ages of 18 and 60, take no other medication or have no other medical conditions, side effects you are more likely to experience include:

  • Irritation, pain, burning, redness, skin discoloration or bruising, or a hematoma at the site of injection.
  • Major bleeding at any site (including in the brain or abdomen) is a risk with enoxaparin use, although the overall reported incidence is low. A fall in hematocrit (the number of red blood cells in the blood) or a drop in blood pressure should prompt a search for a bleeding site.
  • Other side effects include anemia, edema, shortness of breath, diarrhea, and confusion.
  • Not suitable for people with pre-existing bleeding disorders.
  • Only available as an injection that is administered under the skin.
  • The dosage of enoxaparin requires adjusting for severe renal impairment.
  • LMWHs, such as enoxaparin, have been associated with spinal and epidural hematomas (solid clotted areas of blood) in people receiving spinal anesthesia or undergoing spinal puncture. The risk is greater in those with indwelling epidural catheters, taking other medications that also affect blood clotting, undergoing repeated procedures, or with a history of spinal deformity or surgery.
  • May not be suitable for some people including those with active major bleeding, certain platelet disorders, low body weight, or with hypersensitivity to enoxaparin, heparin, or pork products. Care should also be taken when using in people with diabetic retinopathy, high blood pressure, recent gastrointestinal ulceration, or kidney disease.
  • May interact with some other medications including those that affect bleeding (such as aspirin, NSAIDs, and platelet inhibitors).
  • Thrombocytopenia (low platelet numbers) has been reported with enoxaparin use. Should be used with caution in people who have a history of thrombocytopenia with heparin.
  • There is limited data on the use of enoxaparin in pregnant women. A retrospective study reviewed the records of 604 women who used enoxaparin during pregnancy. A total of 624 pregnancies resulted in 693 live births. There were 72 hemorrhagic events (11 serious) in 63 women. There were 14 cases of neonatal hemorrhage. Major congenital anomalies in live births occurred at rates (2.5%) similar to background rates. This suggests that enoxaparin does not increase the risk of major developmental abnormalities. Pregnancy alone confers an increased risk for thromboembolism that is even higher for women with thromboembolic disease and certain high-risk pregnancy conditions. Pregnant women with mechanical prosthetic heart valves may be at even higher risk for thrombosis. All patients receiving anticoagulants, including enoxaparin, are at risk for bleeding. Monitor them for evidence of bleeding or excessive anticoagulation. Consider switching to a shorter-acting anticoagulant as delivery approaches. It is unknown whether enoxaparin is excreted in human milk.

Note: In general, seniors or children, people with certain medical conditions (such as liver or kidney problems, heart disease, diabetes, seizures) or people who take other medications are more at risk of developing a wider range of side effects. View complete list of side effects

4. Bottom Line

Enoxaparin is an anticoagulant that is given by an injection just under the skin and is used in the treatment and prevention of deep vein thrombosis and some other conditions. Routine blood tests are not required; however, people administered enoxaparin should be monitored for signs of excessive bleeding.

5. Tips

  • When injecting subcutaneously, ensure the whole length of the needle is introduced to a skin fold held between the thumb and forefinger. There is no need to expel the bubble from the syringe before injecting. Avoid rubbing the injection site after injecting to minimize bruising.
  • Call emergency services immediately if you have any symptoms of thromboembolism (blood clots), such as shortness of breath, pain in the legs, or confusion. People with excess body weight are more at risk of thromboembolism.
  • Report any tingling, numbness, or weakness to your doctor, particularly if you have had a spinal puncture or spinal or epidural anesthesia.
  • Enoxaparin reduces the ability of your blood to clot, so small cuts may take longer to stop bleeding than normal, and you may bruise more easily. Report any unusual bleeding, bruising, or rashes to your doctor.
  • Tell all health professionals, including your dentist, that you are administering/being administered enoxaparin.
  • Tell your doctor if you are pregnant, intending to become pregnant, or breastfeeding because enoxaparin may not be suitable for you.

6. Response and effectiveness

  • The average time to peak effects on various clotting factors is anti-Xa (3 hours), anti-IIa (4 hours), and Heptest (2.5 hours). Activity against anti-Xa persists for about 12 hours following a once-daily dose of enoxaparin 40mg.
  • The recommended dosage of enoxaparin varies depending on what enoxaparin is being used for.

7. Interactions

Medicines that interact with enoxaparin may either decrease its effect, affect how long it works, increase side effects, or have less of an effect when taken with enoxaparin. An interaction between two medications does not always mean that you must stop taking one of the medications; however, sometimes it does. Speak to your doctor about how drug interactions should be managed.

Common medications that may interact with enoxaparin include:

  • apixaban
  • aspirin
  • dabigatran
  • mifepristone
  • NSAIDs, such as ibuprofen, diclofenac, and naproxen
  • tetracyclines, such as doxycycline and minocycline
  • tinzaparin.

In general, any medicine that can increase the risk of bleeding (such as clopidogrel, SSRI antidepressants, and fish oils) may interact with enoxaparin.

Note that this list is not all-inclusive and includes only common medications that may interact with enoxaparin, You should refer to the prescribing information for enoxaparin for a complete list of interactions.


Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use enoxaparin only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Copyright 1996-2023 Revision date: December 30, 2022.