Clexane (Enoxaparin)

How does it work?

Clexane injection contains the active ingredient enoxaparin, which is a type of medicine called a low molecular weight heparin. It is used to stop blood clots forming within the blood vessels.

Blood clots normally only form to stop bleeding that has occurred as a result of injury to the tissues. The clotting process is complicated and begins when blood cells called platelets clump together and produce chemicals that activate the clotting process. The final part of this process involves a substance called thrombin being activated to produce a protein called fibrin. Fibrin binds the platelets together, forming a blood clot. This is the body’s natural way of repairing itself.

Sometimes, however, a blood clot can form abnormally within the blood vessels. This is known as a thrombus. It can be dangerous because the clot may detach and travel in the bloodstream, where it becomes known as an embolus. The embolus may eventually get lodged in a blood vessel, thereby blocking the blood supply to a vital organ such as the heart, brain or lungs. This is known as a thromboembolism.

Some people have an increased tendency for blood clots to form within the blood vessels. This is usually due to a disturbance in the blood flow within the blood vessels. For example, in coronary artery disease, fatty deposits (atherosclerosis) on the walls of the coronary arteries can disrupt the blood flow, giving a tendency for platelets to clump together and start off the clotting process. When a clot has formed in a coronary artery this reduces the flow of blood to the heart and causes chest pain (angina). It can also result in a heart attack.

Slow blood flow in the leg and pelvic veins can also result in clots forming in these veins (deep vein thrombosis). These clots can break off and travel to the lungs (pulmonary embolism). Being immobile for long periods of time, for example due to a severe medical condition or following surgery, can increase the risk of these types of blood clot.

Enoxaparin is used to prevent and treat these types of abnormal blood clots. It works by inactivating thrombin in the clotting process described above. This stops the formation of fibrin, the essential component of blood clots. The medicine is administered by injection under the skin (subcutaneous injection).

Enoxaparin can also be used to prevent blood clotting when it is filtered through a kidney dialysis machine.

What is it used for?

  • Treatment of blood clots in the veins of the leg (deep vein thrombosis).
  • Treatment of blood clots that travel to the lungs (pulmonary embolism).
  • Preventing these types of blood clots (thromboembolic disorders), particularly following general surgery or surgery on the bones (orthopaedic surgery), or in people bedridden due to illness.
  • Treating blood clots in the coronary arteries in unstable angina and heart attack (myocardial infarction).
  • Preventing blood from clotting when it is filtered through an 'artificial kidney' (haemodialysis) machine as part of the management of kidney failure.


  • During treatment with this medicine you should have regular blood tests to monitor the numbers of blood cells called platelets in your blood.
  • Your doctor may also want to monitor the level of potassium in your blood while you are having this medicine, particularly if treatment lasts for longer than 7 days.

Use with caution in

  • People over 80 years of age.
  • People who are underweight or overweight.
  • Decreased kidney function.
  • Chronic kidney failure.
  • Decreased liver function.
  • People who have previously developed a reduced platelet count in the blood due to treatment with heparin or low molecular weight heparin (heparin-associated thrombocytopenia).
  • People with problems stopping bleeding.
  • History of peptic ulcer.
  • Recent stroke caused by a blood clot in the brain (ischaemic stroke).
  • Severe uncontrolled high blood pressure (hypertension).
  • Diabetes.
  • Diabetes affecting the eyes (diabetic retinopathy).
  • People who have recently had eye surgery.
  • People who have recently had surgery on the brain or spinal cord (neurosurgery).
  • People having spinal or epidural anaesthesia.
  • High level of potassium in the blood (hyperkalaemia).
  • Increase in the acidity of the blood (metabolic acidosis).

Not to be used in

  • Allergy to heparin or other low molecular weight heparins.
  • Bacterial infection of the heart valves and the lining surrounding the heart (bacterial endocarditis).
  • Active major bleeding.
  • Conditions with a high risk of uncontrolled bleeding, for example the blood clotting disorder haemophilia, or the conditions listed below.
  • Active peptic ulcer.
  • Recent stroke caused by bleeding in the brain (haemorrhagic stroke).
  • Reduced platelet count in the blood (thrombocytopenia).
  • This medicine is not recommended for use in children.

This medicine should not be used if you are allergic to one or any of its ingredients. Please inform your doctor or pharmacist if you have previously experienced such an allergy.If you feel you have experienced an allergic reaction, stop using this medicine and inform your doctor or pharmacist immediately.

Pregnancy and breastfeeding

Certain medicines should not be used during pregnancy or breastfeeding. However, other medicines may be safely used in pregnancy or breastfeeding providing the benefits to the mother outweigh the risks to the unborn baby. Always inform your doctor if you are pregnant or planning a pregnancy, before using any medicine.

  • The safety of this medicine for use during pregnancy has not been established. It is not recommended for use in pregnancy unless considered essential by your doctor. It is not recommended for preventing blood clots in pregnant women with artificial heart valves. Seek medical advice from your doctor.
  • It is not known if this medicine passes into breast milk. Mothers who need treatment with this medicine should avoid breastfeeding their infants during the treatment. Seek further medical advice from your doctor.

Side effects

Medicines and their possible side effects can affect individual people in different ways. The following are some of the side effects that are known to be associated with this medicine. Just because a side effect is stated here does not mean that all people using this medicine will experience that or any side effect.

  • Bleeding.
  • Pain and irritation at the injection site.
  • Blood clots which form a solid swelling at the injection site (haematoma).
  • Decrease in the number of platelets in the blood (thrombocytopenia).
  • Major bleeding (haemorrhage), for example in the abdomen or inside the skull.
  • Alteration in results of liver function tests.
  • High blood potassium level (hyperkalaemia).
  • Death of skin cells (necrosis) at the site of injection.
  • Blood clots in the spinal cord (intraspinal haematoma) in people also having spinal or epidural anaesthesia.
  • Osteoporosis (a reduction in bone density leading to bones which may fracture easily) has occurred after long-term treatment with a similar medicine called heparin. It is possible that this could happen with Clexane.

The side effects listed above may not include all of the side effects reported by the drug's manufacturer.For more information about any other possible risks associated with this medicine, please read the information provided with the medicine or consult your doctor or pharmacist.

How can this medicine affect other medicines?

It is important to tell your doctor or pharmacist what medicines you are already taking, including those bought without a prescription and herbal medicines, before you start treatment with this medicine. Similarly, check with your doctor or pharmacist before taking any new medicines while having treatment with this one, to ensure that the combination is safe.

There may be an increased risk of bleeding or increased time taken to stop bleeding, if this medicine is used in combination with medicines that affect blood clotting, such as the following:

  • antiplatelet ('blood-thinning') medicines, such as aspirin, dipyridamole, clopidogrel
  • clot-busting medicines (fibrinolytics) such as streptokinase, alteplase
  • non-steroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen, diclofenac, naproxen
  • oral anticoagulants, such as warfarin, nicoumalone, phenindione.

There may be an increased risk of a rise in the amount of potassium in your blood if this medicine is used in combination with any of the following:

  • ACE inhibitors, eg captopril, lisinopril
  • ciclosporin
  • potassium-sparing diuretics, eg spironolactone, triamterene, amiloride
  • potassium supplements
  • potassium-containing salt substitutes.

The amount of potassium in your blood should be regularly monitored if you are taking any of these during treatment with this medicine.

Other medicines containing the same active ingredient

There are currently no other medicines available in the UK that contain enoxaparin as the active ingredient.