Heparin Administration

Subcutaneous Injections: Heparin

Indications for Administration:

  • Heparin and low molecular-weight heparin (LMWH) are anticoagulants. There are several low-molecular-weight heparins available: enoxaparin (Lovenox), dalteparin (Fragmin), tinzaparin (Innohep), nadroparin (Fraxiparine), reviparin (Clivarin) and certoparin (Sandoparin). LMWH is effective for the prevention of venous thrombosis and has greater bioavailability, more predictable dose response, and longer half-life than heparin. LMWH does not require the same close monitoring and dosage adjustment as heparin.
  • Heparin can be administered IV or subcutaneously. LMWH is administered subcutaneously.


Heparin acts directly on the intrinsic and extrinsic pathways of the coagulation cascade by inhibiting thrombin-mediated conversion of fibrinogen to fibrin, potentiating the actions of antithrombin III, inhibiting the activation of factor IX, and activating factor X inhibitor (which neutralizing activated factor X).

View an animation of blood clotting and the coagulation cascade at:

Patient Assessment

  • Know side effects and adverse reactions to heparin or low molecular-weight heparin
  • Assess for bleeding (hematuria, bleeding from the gums, retroperitoneal bleeding, occult bleeding)
  • Evaluate aPTT (activated partial thromboplastin time) before giving therapeutic doses of Heparin or Lovenox. Prophlactic doses are low dose injections (~5,000 units) once or possibly twice a day. PTT's are not normally ordered for prophlactic doses.

Sites of Administration

Administering Heparin

  • Administer subcutaneously in the abdomen.
  • Do NOT aspirate.
  • Do NOT massage the site after administration.
  • Have antidote for heparin overdose available. The usual dose of protamine sulfate is 1 mg IV for every 100 units of heparin administered.