Heparin Overdose

Heparin Overdose

Heparin is blood thinner that is given to patients in order to prevent blood clot formation. It has its own therapeutic window and any amount that is higher than this range may lead to an overdose of heparin [1, 2].

What is Heparin?

The main function of heparin is to prevent the conversion of clotting factors to avoid the formation of blood clots. Heparin is usually given to patients who will undergo a surgical procedure to decrease the chance of clotting. It is also used to maintain the patency of intravenous catheters or as a lock flush.

One of the potential side effects of taking this drug is the possibility of bleeding. The physician must be advised once signs of bleeding such as easy bruising, presence of black, tarry stools, nosebleed, blood in the urine or any bleeding that fails to stop.

The bleeding time of patients who take this medication are monitored because there may be a need to adjust the dosage of the drug depending on the results of these tests [1, 2, 3, 4, 5].

How much Heparin Overdose?

The amount of heparin that is toxic to individuals depend from one individual to another. The bleeding time of the patient is the basis for the toxicity. A person is considered to overdose on heparin if their ability to form blood clots is impaired [1, 2, 3].

What are Heparin Overdose symptoms?

The main symptom of an heparin overdose is the occurrence of bleeding. The patient will experience GI bleeding as evidenced by vomiting of blood or appearance of tarry or black stools.

There may even be nosebleeds and the presence of blood in the urine. These are just the initial signs of bleeding in the patient. The presence of unexplained bruises or petechial formations may indicate the possibility of frank bleeding [2, 4, 5].

What is Heparin Overdose management?

If an individual experiences bleeding due to an increased level of heparin in the blood, the drug protamine sulfate may be given by slow infusion.

1mg of protamine sulfate is needed to neutralize 100 units of heparin although the maximum amount that can be given in a 10-minute period is 50mg.

The drug required to counteract heparin reduces over time as the body starts to metabolize heparin. The side effects associated to taking protamine include hypotension and anaphylaxis reaction. Due to the severity of anaphylactic reaction to protamine, anaphylactic treatment and resuscitation equipment must be on standby when giving this drug [2, 4, 5].

How to prevent Heparin Overdose?

The primary way to prevent heparin overdose is to take the drug as instructed by the physician. Double check the dosage before administration to be ensure that it is the correct dose. Any signs of bleeding must be noted and reported to the physician in order to be addressed immediately.

Regular blood coagulation tests must be performed while receiving heparin therapy to monitor the effect of the drug in the bleeding time of the patient [2, 4, 5]. 

Heparin overdose is serious and can lead to death if it is not managed on time. If you know more about this condition, feel free to comment below.


  1. Drugs.com. (2016, September 6). Heparin. Retrieved from Drugs.com: https://www.drugs.com/drug-interactions/heparin.html
  2. RxList. (2012, January 23). Heparin. Retrieved from RxList: http://www.rxlist.com/heparin-drug.htm
    Cerner Multum. (2012, February 14).
  3. Heparin. Retrieved from eMedicineHealth: http://www.emedicinehealth.com/drug-heparin/article_em.htm
  4. WebMD. (2016). Heparin (Bovine) Injection. Retrieved from WebMD: http://www.webmd.com/drugs/2/drug-5664/heparin-bovine-injection/details#overdose
  5. Medscape. (2016). Heparin. Retrieved from Medscape: http://reference.medscape.com/drug/calciparine-monoparin-heparin-342169#5

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