Anticoagulant
Heparin (unfractionated)
Brand names: Heparin sodium
Adult dose
Dose: Treatment IV: loading 75–80 units/kg bolus, then 18 units/kg/h infusion, adjusted by APTT (target ratio 1.5–2.5). Prophylaxis SC: 5000 units BD–TDS
Route: IV/SC
Frequency: continuous or BD-TDS
Clinical pearls
- Reversal: protamine 1mg per 100 units heparin given in last 2–3h, max 50mg
- Preferred over LMWH where short half-life advantage needed (e.g. peri-operative, severe renal impairment)
Contraindications
- Active major bleeding
- Severe thrombocytopenia
- HIT history (use alternative anticoagulant)
- Recent intracranial haemorrhage
- Severe uncontrolled hypertension
Side effects
- Bleeding
- Heparin-induced thrombocytopenia (HIT type II)
- Osteoporosis (long-term)
- Hyperkalaemia
- Skin necrosis at injection site
Interactions
- Antiplatelets/other anticoagulants — bleeding
- NSAIDs
- ACEi/ARB (hyperkalaemia)
Monitoring
- APTT (treatment)
- Platelets (HIT screening days 4–14)
- K+ (prolonged use)
Reference: BNF; NICE NG89; ESC guidelines; https://bnf.nice.org.uk/drugs/heparin/. Verify against your local formulary and the latest BNF before prescribing.
Related
Curated clinical cross-links plus same-class fallbacks.
Calculators
- DOAC Score for Selecting Direct Oral Anticoagulant in Non-Valvular AF · Anticoagulation
- Corrected Sodium (Hyperglycaemia) · Electrolytes
- Hyponatraemia Cause Algorithm · Electrolyte Disorders
- MELD-Na Score · Liver Disease
- MELD-Na Score for Liver Cirrhosis · Hepatology
- 4Ts Score for Heparin-Induced Thrombocytopenia · Thrombocytopenia
Pathways
- Major Haemorrhage / Massive Transfusion · BCSH; RCOA; RCEM; RCS — BCSH Guidelines
- Anaemia Investigation · BSH / NICE
- Splenomegaly Workup · BSH; BMJ Best Practice
- Deep Vein Thrombosis Diagnosis and Treatment · NICE CG144 / NICE NG158
- Sickle Cell Crisis · BSH 2021 / BCSH
- Neutropenic Sepsis · NICE CG151 2012 / ESMO