Heparin is a drug that must be administered with care. In this lesson, you will learn about the indications, adverse effects, and nursing considerations to keep in mind when administering heparin to a patient.

What Is Heparin?

Imagine that you are a nurse on the unit and a patient is being admitted for treatment of deep venous thrombosis (DVT). What would you expect the doctor to prescribe to treat this condition?

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If you guessed heparin (or some other anticoagulant), you would be correct!

Heparin is an anticoagulant, or a blood thinner. It means exactly what it sounds like: it thins your blood in order to prevent clots from forming in your blood vessels. Specifically, it inhibits the conversion of prothrombin to thrombin, which is a vital part of the coagulation cascade.

Heparin is commonly prescribed for the following conditions:

  • Venous thrombosis
  • Pulmonary embolism

As you probably know, the conditions mentioned above occur when there is an abnormal clot that forms in the body. Therefore, it makes sense that you would want to take an anticoagulant to bust that clot open!

Okay, so what do I need to do as a nurse?

Great question. As a nurse, you will need to be aware of how to properly administer heparin, as well as be aware of potential adverse effects. You should also know why are you giving heparin to your patient in the first place. If your patient doesn’t need heparin, then why are you giving it?


Heparin should not be given in the following situations:

  • Patients with conditions that predispose them to bleeding, such as thrombocytopenia, cerebrovascular disorders, stomach ulcers, and hemorrhagic blood disorders
  • Patients who have recently had surgery
  • Patients who have severe uncontrolled hypertension

If, upon your assessment, you realize that your patient has a medical condition that would predispose them to active bleeding, notify the physician immediately. Do not administer the heparin.


If everything checks out and it is okay to administer the heparin to your patient, then you will be giving the heparin via injection. Heparin can be administered subcutaneously (SQ), under the skin, or intravenously (IV), into a vein. Heparin cannot be given intramuscularly (IM). If administering it SQ, do not massage the site after injection. If you will be giving multiple SQ injections, it’s probably a good idea to rotate the sites as well.

Adverse Effects

After administering heparin, you will need to be on the lookout for certain adverse effects. The most obvious, and most important one of these is…

You guessed it: Bleeding. You may see bleeding in the urine, bleeding from the oral and nasal mucosa, and excessive bleeding from any wounds the patient may have.

Nursing Implications

In order to prevent this from happening, the physician will write for a blood test known as the partial thromboplastin time (PTT) or the activated partial thromboplastin time (APTT). Basically, this blood test determines how long it takes for your blood to clot. It is also used to determine if the correct dose of heparin is being given. Now, normal ranges vary from lab to lab, but a typical reference range might look like this:



The medical team will adjust the dose of heparin until it reaches the therapeutic level of 1.5 to 2.5 times the normal value.

In cases of severe heparin overdose, the antidote is protamine sulfate. The dose of protamine sulfate will depend on the dose of heparin that was given.

Lesson Summary

Heparin is classified as an anticoagulant, or a blood thinner. It is prescribed when an individual suffers from a condition that predisposes them to having blood clots in their body. Heparin is administered subcutaneously or intravenously. A major adverse effect of heparin is bleeding.

The nurse will draw labs measuring the patient’s partial thromboplastin time (PTT) and/or active partial thromboplastin time (APTT) to determine if the proper dose of heparin is being given. The dose may be adjusted until the patient’s PTT/APTT reaches the desired therapeutic level of 1.5 to 2.5 times the patient’s normal values.

Medical Disclaimer: The information on this site is for your information only and is not a substitute for professional medical advice.