Anticoagulant — VTE Prophylaxis (UFH)

Heparin Unfractionated (Prophylaxis)

Brand names: Heparin Sodium (generic)

Unfractionated heparin is a parenteral anticoagulant used for venous thromboembolism prophylaxis and treatment in the surgical setting.

Dosing — being independently re-sourced

ClinCalc Pro is rebuilding its dose data from primary open sources — the manufacturer SmPC (eMC), the WHO Model Formulary and other official references — under clinician review. This drug's structured dose is not yet published here. Confirm all doses against the product SmPC and your local formulary before prescribing.

Clinical monograph

How it works

It potentiates antithrombin, accelerating inactivation of thrombin (factor IIa) and factor Xa, thereby inhibiting clot formation.

Prescribing in practice

Bleeding is the main risk; assess bleeding risk against thrombotic risk and remember protamine is available for reversal.
Heparin-induced thrombocytopenia is an important immune-mediated complication; monitor platelets and stop if suspected.
It has a short half-life, making it useful where rapid offset or reversibility is desirable, such as around surgery.

Monitoring

Monitor for bleeding and platelet count, with APTT monitoring used when given at treatment (rather than prophylactic) intensity.

Counselling the patient

Report unusual bruising, bleeding or black stools promptly.
Tell the team about any history of low platelets or reaction to heparin.

Evidence & guidelines

NICE guidance on venous thromboembolism (NG89) supports pharmacological prophylaxis in surgical patients after individual risk assessment.

Reference: ASRA Guidelines; NICE NG89; BCSH Heparin Guidelines; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways