The Use of Heparin in Stroke and Other Diseases

Heparin is a blood thinning medication used to prevent blood clot formation. Heparin can be given either directly into the bloodstream or as an injection under the skin. No oral form of heparin is available, and that is why it is typically used in the hospital setting.

Nurse comforting older female patient
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Use in the Hospital

Heparin prevents the formation of blood clots. Some of the most common reasons heparin is used include:

  • To prevent the formation of the blood clots that can form as a complication of staying in bed for prolonged periods of time: A low daily dose of heparin is typically injected under the skin to help prevent the formation of deep venous thromboses (DVT) in the veins of the legs, thighs, and pelvis. DVTs may also cause strokes and pulmonary embolisms (PE), which can be life-threatening.
  • To treat pulmonary embolisms: Pulmonary embolisms are blood clots that migrate into the lungs from the heart, or from the deep venous system of the body. Once in the lungs, pulmonary embolisms can block blood flow to large portions of the lung and prevent oxygen-poor, venous blood from receiving oxygen.
  • To prevent the enlargement of high-risk blood clots found inside the heart, and other parts of the body, as they can cause pulmonary embolisms or strokes.
  • To prevent the formation of blood clots during heart surgery, or during surgery of the large arteries.

When Is Heparin Used to Treat Stroke?

Heparin is also used to treat strokes that are caused by identifiable blood clots. Some of the situations that strongly suggest that a stroke is associated with a blood clot include:

Intravenous Heparin Dosage

Unlike most medications, the dose of heparin must be chosen according to the results of a blood test called the partial thromboplastin time (PTT). Once an intravenous infusion of heparin is started, its dose is adjusted every four to six hours in order to ensure that blood does not become so thin that a person runs the risk of spontaneous bleeding.

Most heparin treatment protocols call for a one-time "bolus injection" of heparin followed by a slow increase of the dose to a PTT that is roughly twice the normal value.

Because there is no oral form of this medication, heparin must be stopped before a person leaves the hospital. People who need long-term therapy with blood thinners are commonly prescribed Coumadin (warfarin), Eliquis (apixaban), or one of the other blood thinners that are available in a tablet form. Lovenox (enoxaparin sodium) is a type of heparin that can be self-administered via injection.

Coumadin is started while a person is still receiving intravenous heparin, but once blood tests show that Coumadin's blood-thinning effect is adequate, heparin can be stopped. This is done because Coumadin can take up to 72 hours before its desired effect is reached.

Side Effects

The main side effect of heparin is bleeding. For this reason, it is important that physicians track blood counts when people are being treated with intravenous heparin in order to ensure that blood counts remain stable. Spontaneous bleeding can occur from several places in the body, including:

  • Open wounds or surgical sites
  • Stomach and intestines
  • Uterus and ovaries
  • Gums and mouth

In cases of profuse bleeding due to heparin treatment, a medication called protamine sulfate can be given intravenously to neutralize heparin's blood-thinning effect. In cases of severe bleeding, blood transfusions are required to replace the blood lost.

Another important side effect of heparin is a condition known as heparin-induced thrombocytopenia (HIT). In this condition, heparin induces the body's immune system to develop antibodies against its own platelets. Since a normal level of platelets is required by the body to prevent bleeding, a low level of platelets places people at risk of major bleeding.

Paradoxically, this same condition can also cause the inappropriate and spontaneous formation of large blood clots, which can block blood flow through important blood vessels and damage the kidneys, the skin, and the brain, among other organs.

A Word From Verywell

Heparin is a medication that must be maintained at a dose based on the body's response to the blood-thinning action. This necessitates close follow up with blood tests that can measure the effect of heparin to ensure that the action is maintained within a therapeutic window.

If you have had to receive treatment with heparin, it is likely that you will be switched to another blood thinner for the long run.

2 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. National Institutes of Health. MedlinePlus. Heparin injection. Reviewed September 15, 2017.

  2. Suero-Abreu GA, Cheng JZ, Then RK. Multiple recurrent ischaemic strokes in a patient with cancer: Is there a role for the initiation of anticoagulation therapy for secondary stroke prevention? BMJ Case Rep. 2017;2017:bcr2016218105. doi:10.1136/bcr-2016-218105

By Jose Vega MD, PhD
Jose Vega MD, PhD, is a board-certified neurologist and published researcher specializing in stroke.