Does heparin cause side effects?

Heparin is an injectable anticoagulant used to stop the formation of blood clots. The blood coagulation system is composed of various steps and heparin acts at multiple sites in this process. 

Heparin prevents blood clots by blocking the action of 4 of the 12 clot-promoting proteins in blood (factors II, VII, IX, X) whose action is necessary for blood to clot. Brand names available for heparin include Hemochron, Hep-Lock, Hep-Lock U/P, Heparin in 5% Dextrose, Heparin Lock Flush, HepFlush-10.

Common side effects of heparin include

Serious side effects of heparin include severe bleeding.

Drug interactions of heparin include medications that increase the risk of bleeding such as aspirin, clopidogrel, warfarin, other anticoagulants, and nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen, naproxen, diclofenac, and others, because these add to the effects of heparin and further increase the risk of bleeding that is associated with heparin. 

Heparin has not been adequately evaluated in pregnant women. Heparin should only be used during pregnancy if the potential benefit justifies the potential risk to the fetus. Preservative-free heparin is recommended when heparin is needed during pregnancy. 

It is unknown if heparin is excreted into breast milk. Due to its large molecular weight, it is thought heparin is not likely to be excreted into breast milk. Preservative-free heparin is recommended when heparin is needed during breastfeeding.

What are the important side effects of heparin?

The most common side effects are hemorrhage (bleeding), thrombocytopenia (decrease platelet count), heparin induced thrombocytopenia (HIT), heparin induced thrombocytopenia and thrombosis (HITT), injection site discomfort/irritation, allergy or hypersensitivity type reactions, and increase in liver enzymes.

Heparin side effects list for healthcare professionals

Hemorrhage

Hemorrhage is the chief complication that may result from heparin therapy. An overly prolonged clotting time or minor bleeding during therapy can usually be controlled by withdrawing the drug. It should be appreciated that gastrointestinal or urinary tract bleeding during anticoagulant therapy may indicate the presence of an underlying occult lesion. Bleeding can occur at any site but certain specific hemorrhagic complications may be difficult to detect:

  1. Adrenal hemorrhage, with resultant acute adrenal insufficiency, has occurred during anticoagulant therapy. Therefore, such treatment should be discontinued in patients who develop signs and symptoms of acute adrenal hemorrhage and insufficiency. Initiation of corrective therapy should not depend on laboratory confirmation of the diagnosis since any delay in an acute situation may result in the patient's death.
  2. Ovarian (corpus luteum) hemorrhage developed in a number of women of reproductive age receiving short- or long-term anticoagulant therapy. This complication if unrecognized may be fatal.
  3. Retroperitoneal hemorrhage.

Hypersensitivity

Generalized hypersensitivity reactions have been reported with chills, fever, and urticaria as the most usual manifestations, and asthma, rhinitis, lacrimation, headache, nausea and vomiting and anaphylactoid reactions, including shock, occurring more rarely. Itching and burning, especially on the plantar site of the feet may occur.

Thrombocytopenia has been reported to occur in patients receiving heparin with a reported incidence of 0 to 30%. While often mild and of no obvious clinical significance, such thrombocytopenia can be accompanied by severe thromboembolic complications such as

Certain episodes of painful, ischemic and cyanosed limbs have in the past been attributed to allergic vasospastic reactions. Whether these are in fact identical to the thrombocytopenia associated complications remains to be determined.

Miscellaneous

  • Osteoporosis following long-term administration of high doses of heparin, cutaneous necrosis after systemic administration, suppression of aldosterone synthesis, delayed transient alopecia, priapism and rebound hyperlipemia on discontinuation of heparin sodium have also been reported.
  • Significant elevations of aminotransferase (SGOT [S-AST] and SGPT [S-ALT]) levels have occurred in a high percentage of patients (and healthy subjects) who have received heparin.

What drugs interact with heparin?

Oral anticoagulants
  • Heparin sodium may prolong the one-stage prothrombin time. Therefore, when heparin sodium is given with dicumarol or warfarin sodium, a period of at least 5 hours after the last intravenous dose should elapse before blood is drawn if a valid Prothrombin time is to be obtained.
Platelet inhibitors
Other interactions

Drug/Laboratory Test Interactions

Hyperaminotransferasemia
  • Significant elevations of aminotransferase (SGOT [S-AST] and SGPT [SALT]) levels have occurred in a high percentage of patients (and healthy subjects) who have received heparin.
  • Since aminotransferase determinations are important in the differential diagnosis of myocardial infarction, liver disease, and pulmonary emboli, rises that might be caused by drugs (like heparin) should be interpreted with caution.

Treatment & Diagnosis

Medications & Supplements

FDA Logo

Report Problems to the Food and Drug Administration

You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.

Medically Reviewed on 11/12/2020
References
FDA Prescribing Information

Professional side effects and drug interactions sections courtesy of the U.S. Food and Drug Administration.