DermNet NZ



Heparin-induced skin necrosis

What is heparin-induced skin necrosis?

Heparin-induced skin necrosis (heparin necrosis) is a rare complication of heparin injections either at the injection site or distant sites, in which there is death of skin cells (necrosis) due to inadequate blood supply. One form, heparin-induced thrombocytopaenia (HIT), is associated with a fall in platelet count and paradoxical formation of clots in blood vessels.

Who gets heparin-induced necrosis?

Heparin necrosis can affect adults receiving subcutaneous or intravenous heparin injections either to treat established deep venous thrombosis (DVT) or to prevent this occurring when they are at risk of developing DVT such as following surgery or prolonged hospitalization. Women appear to be more commonly affected than men.

Clinical features

Heparin necrosis begins on average 7 days (range 1-17 days) after starting heparin injections. Redness, pain and swelling under the skin develop at the heparin injection sites. Within hours or 1-2 days blisters develop and then a black-red centre appears due to skin necrosis (death of skin cells). There is surrounding redness and bruising. In many cases it occurs only at the injection site, but it can develop anywhere on the skin with no apparent preferred sites. Usually the area of necrosis is only about 3cm in diameter, but can be more extensive.

Heparin (enoxaparin) induced necrosis Heparin (enoxaparin) induced necrosis Heparin (enoxaparin) induced necrosis
Heparin (enoxaparin) induced necrosis

How is the diagnosis made?




Heparin necrosis can however occur in the absence of these antibodies and the mechanism may then be less clear. Blood tests would also be done for clotting factors, protein C and protein S (usually normal).

It is the combination of the clinical presentation and these results that makes the diagnosis.



Generally ceasing the heparin injections promptly leads to recovery. Wound care involves cleaning and dressing areas of skin loss, with appropriate pain relief. Sometimes surgery is required to remove the dead skin and a skin graft may be performed if this is extensive, resulting in a more prolonged recovery time. If anticoagulation is still required then an alternative drug should be used and this may include aspirin, warfarin, hirudins or unfractionated heparin, depending on the cause of the heparin necrosis. If HIT is excluded a change in heparin type may be used safely.


Proposed mechanisms


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Author: Dr Delwyn Dyall-Smith FACD, Dermatologist

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