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Educational draft · awaiting clinical reviewUse Rapid for revision, not patient-care decisions. Check current national and local guidance and the BNF or BNFC before acting.

Anticoagulation choice and duration

Haematology and transfusion · UK scope · Sources checked 27 Aug 2026 · Clinical review pending

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Unstable thrombosis or major bleeding

Shock, hypoxaemia, limb threat, neurological deficit, ongoing major bleeding or a critical-site bleed makes immediate stabilisation and specialist source control more important than routine oral-drug selection.

Action: Use ABCDE assessment, stop anticoagulants when bleeding is suspected, obtain FBC, coagulation, renal, liver, group and last-dose information, activate the relevant PE, stroke, vascular, obstetric or haemorrhage pathway and use a reversal agent only for its supported indication.

Synopsis

Choose an anticoagulant from the indication, clot context, bleeding risk, organ function and patient priorities, then prescribe a defined duration with a documented review or stopping plan.

  • Define the indication before the drug: venous thromboembolism, atrial fibrillation, mechanical valve, acute coronary disease and thromboprophylaxis use different agents, doses and endpoints.
  • For confirmed proximal DVT or PE, NICE recommends at least 3 months of anticoagulation; review at 3 months whether the event was provoked, unprovoked, cancer associated or still supported by a persistent risk.
  • Apixaban or rivaroxaban is a first-line option for most adults with DVT or PE when renal function, interactions, body context, adherence and bleeding risk permit.
  • Dabigatran and edoxaban require at least 5 days of therapeutic parenteral anticoagulation before their VTE treatment phase; apixaban and rivaroxaban use an oral loading phase instead.
  • Use a vitamin K antagonist rather than a DOAC for a mechanical prosthetic valve; warfarin is also generally preferred for thrombotic antiphospholipid syndrome, especially triple-positive disease.
  • Calculate creatinine clearance with Cockcroft–Gault for DOAC dosing: an automatically reported eGFR can overestimate function in older, low-weight or acutely unwell adults.
  • A transient provoking factor that has resolved usually supports stopping after the treatment course; unprovoked or persistent-risk VTE requires an explicit recurrence-versus-bleeding discussion and at least annual review if continued.
  • Do not use a bleeding score as the sole reason to withhold indicated anticoagulation; identify modifiable hazards such as uncontrolled hypertension, interacting antiplatelets, alcohol excess and untreated bleeding lesions.
  • Record the exact medicine, indication, dose, renal calculation, intended duration, review date, missed-dose advice and peri-procedural contact route at every transition of care.

Key red flags

Haemodynamic instability, syncope, severe hypoxaemia or right-heart strain with suspected PE requires an emergency reperfusion assessment rather than an ordinary outpatient anticoagulation decision.

Head injury, new focal neurology, severe headache, gastrointestinal haemorrhage, haemodynamic compromise or a rapid haemoglobin fall while anticoagulated requires urgent bleeding assessment and source control.

Pregnancy, a mechanical valve, severe renal failure, active cancer, antiphospholipid syndrome, thrombocytopenia or suspected heparin-induced thrombocytopenia changes the usual drug pathway and needs specialist input.

Investigation priorities

01
First-line: FBC, renal, liver and weight assessmentFirst stepFirst line

Establish bleeding reserve and calculate a safe agent-specific dose.

02
Selective antiphospholipid testingPreferred

Detect a condition that can change the preferred long-term anticoagulant.

Management branches

Confirmed acute VTESelect and start treatment

Objective imaging confirms proximal DVT or PE and there is no immediate reperfusion indication.

  1. Assess haemodynamics, bleeding, renal and liver function, weight, pregnancy, cancer, APS and interactions.
  2. Use apixaban or rivaroxaban when suitable, or give therapeutic heparin before dabigatran, edoxaban or a vitamin K antagonist pathway.
  3. Give written dose-phase instructions and set a 3-month review before discharge or handover.

Key medicines

ApixabanFor acute DVT or PE give 10 mg orally twice daily for 7 days, then 5 mg twice daily; after 6 months, 2.5 mg twice daily may be used for extended prevention when continued treatment is chosen.Use the indication-specific SmPC renal criteria; do not apply AF dose-reduction rules to acute VTE. Avoid active major bleeding and strong dual CYP3A4/P-gp interactions, review severe renal or hepatic impairment, and avoid during pregnancy or breastfeeding.
RivaroxabanFor acute DVT or PE give 15 mg orally twice daily with food for 21 days, then 20 mg once daily with food; after at least 6 months, 10 mg once daily is an extended-prevention option, with 20 mg considered when recurrence risk is high.The 15 mg and 20 mg tablets must be taken with food. Use Cockcroft–Gault renal assessment, avoid CrCl below 15 mL/min, active bleeding and strong combined CYP3A4/P-gp inhibitors, and assess gastrointestinal bleeding, liver disease, pregnancy and adherence.
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Sources and review status6 sources · checked 27 Aug 2026 · clinical review pending+
Sources

Sources and review status

National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 27 Aug 2026; clinical approval remains outstanding.

  • NICE NG158 venous thromboembolic diseases recommendationsUK diagnosis, treatment choice and duration recommendations for DVT and PE.
  • NICE NG196 atrial fibrillation recommendationsUK stroke-risk, bleeding-risk and anticoagulant selection guidance.
  • MHRA renal-function estimate for medicine dosingCockcroft–Gault use for DOAC dosing and vulnerable groups.
  • Apixaban Summary of Product CharacteristicsLicensed VTE regimens, contraindications and interaction information.
  • Rivaroxaban Summary of Product CharacteristicsLicensed acute and extended VTE regimens and safety modifiers.
  • Lixiana Summary of Product CharacteristicsEdoxaban heparin lead-in and renal, weight and interaction dose criteria.

Editorial contact: Doctor’s Passport editorial team. Source-check date is separate from clinical approval. Report a content problem · Content changes

Authoring stateRapid draftClinical stateAwaiting reviewJurisdictionUnited Kingdom