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Enoxaparin: 6 things you should know

Medically reviewed by C. Fookes, BPharm Last updated on Aug 28, 2018.

1. How it works

  • Enoxaparin is an anticoagulant that works by binding to and accelerating the activity of antithrombin III. This inhibits the activity of clotting factors Xa and IIa. Thrombin production is decreased which prevents fibrin clot formation.
  • Enoxaparin belongs to the class of medicines known as low molecular weight heparins (LMWH).

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.

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, 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 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.
  • Dosage of enoxaparin requires adjusting in 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, a low body weight or with a 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 also have an effect on 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.
  • Limited information exists regarding the use of enoxaparin in pregnant women with prosthetic heart valves.

Notes: 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. For a complete list of all side effects, click here.

4. Bottom Line

Enoxaparin is an anticoagulant that 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.

6. Response and Effectiveness

  • Average time to peak effects on various clotting factors are: anti-Xa (3 hours), anti-IIa (4 hours), 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.


Enoxaparin [Package Insert]. Revised 06/2018. Amphastar Pharmaceuticals, Inc.

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.

Copyright 1996-2019 Revision date: August 28, 2018.

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