Cardiovascular / Haematology
DOACs
Direct oral anticoagulants — Modern anticoagulants for AF and venous thrombosis that usually need no routine INR monitoring.
Education and reference only. This is a plain-language class overview — it deliberately contains no doses. Always check the current Summary of Product Characteristics (SmPC), the BNF and your local formulary before prescribing or administering any medicine.
What it is
Direct oral anticoagulants are widely used to prevent stroke in atrial fibrillation and to treat and prevent deep vein thrombosis and pulmonary embolism. For many patients they have replaced warfarin because they work at fixed doses without routine blood-level monitoring.
How it works
They directly inhibit a single clotting factor: either factor Xa (the "-xaban" drugs) or thrombin (dabigatran). This interrupts the clotting cascade and reduces the formation of harmful clots, while still carrying a bleeding risk that must be balanced against the benefit.
In practice
In practice the commonest errors are using the wrong dose for the indication and missing renal decline. Confirm the indication-specific dose against the SmPC, document the patient's weight, age and renal function, and set a recall to recheck kidney function — at least yearly, sooner if they become unwell. Unlike warfarin there is no INR to flag drift, so the review interval you set is the safety net.
Examples
Practical use
How to take it & use it well
- Take it at the same time each day. Some types are once daily and some are taken more than once a day, so follow your specific instructions exactly.
- Some of these medicines should be taken with food to be absorbed properly, while others can be taken with or without, so check which applies to yours.
- If you miss a dose, the right action depends on which medicine you take and how often, so ask your pharmacist rather than guessing. Never double up to catch up.
- Do not stop taking it without advice, as your protection against clots and stroke is lost quickly once the medicine wears off.
- Carry an anticoagulant alert card and tell any dentist, doctor or surgeon that you take a blood thinner before any procedure.
- Watch for unusual bruising, blood in your urine or stools, or bleeding that will not stop, and seek urgent advice if this happens.
Common uses
- Stroke prevention in non-valvular atrial fibrillation
- Treatment of DVT and pulmonary embolism
- Extended VTE prevention after some surgery
Monitoring
- Renal function at least annually, and more often if impaired or unwell
- Full blood count and bleeding signs
- Weight and age at review (can affect dose choice)
Weighing it up
Advantages & disadvantages
Advantages
- They reduce the risk of stroke and dangerous blood clots without the routine blood-test monitoring that warfarin needs.
- They work at a steady, predictable level, so most people take a fixed dose.
- They have fewer food interactions than warfarin, so your diet does not need to change.
- They begin to work quickly, which is convenient when treatment is started.
- There are reversal treatments available in hospital for serious bleeding with some of these drugs.
Disadvantages
- Like all blood thinners, they increase the risk of bleeding, which can sometimes be serious.
- They are not suitable for everyone, including people with certain heart valves or very poor kidney function.
- Missing doses matters more than with warfarin because they leave the body relatively quickly.
- They can be more expensive than warfarin, and not all have a specific reversal agent.
- Kidney function needs checking regularly because it affects how the medicine is cleared.
Key safety principles
What to watch for
- Dose depends on the indication and on factors such as renal function, age and weight — always confirm against the SmPC/BNF.
- Reduced kidney function increases drug levels and bleeding risk; some agents are avoided below a renal threshold.
- Not suitable for mechanical heart valves or significant mitral stenosis.
- Many interactions (e.g. some antifungals, antiepileptics, rifampicin) alter drug levels.
Key interactions
What to avoid or check alongside
- Taking them with anti-inflammatory painkillers (NSAIDs) or aspirin raises the risk of bleeding.
- Other blood thinners or clot-busting medicines greatly increase bleeding risk and are not normally combined.
- Certain antifungal and some HIV medicines can raise the level of these drugs and increase bleeding.
- The herbal remedy St John's wort and some epilepsy medicines can lower their effect and reduce protection against clots.
- Heavy alcohol use increases bleeding risk and is best avoided.
- Some antibiotics can affect their levels, so always mention you take a blood thinner.
Patient & carer advice
- Take exactly as prescribed — missing doses leaves you unprotected, doubling up increases bleeding
- Report unusual bruising, blood in urine or stool, or black stools
- Tell any dentist or surgeon you take an anticoagulant
Use with
Related clinical calculators
Dose and risk decisions for this class often depend on renal function, weight or bleeding/stroke risk. These tools help:
Answers
DOACs: frequently asked questions
Do I need regular blood tests like with warfarin?
Not for the medicine itself, which is a key advantage. You will still have periodic blood tests to check your kidney function and general health.
What should I do if I miss a dose?
It depends on which one you take and how often. Because these medicines leave the body quickly, do not double up. Check with your pharmacist for advice specific to your medicine.
Can I take painkillers with it?
Paracetamol is usually the safer choice. Avoid ibuprofen and similar anti-inflammatory painkillers unless your doctor agrees, as they increase bleeding risk.
Is it safe in pregnancy?
These medicines are generally not recommended in pregnancy. If you are pregnant or planning to be, tell your doctor so a suitable alternative can be arranged.
What do I do before surgery or dental work?
Always tell the dentist, surgeon or doctor that you take a blood thinner. They will advise whether to pause it and for how long, depending on the procedure.
Authoritative sources
Always verify against the source
This overview is for orientation. For doses, interactions, contra-indications and the full monograph, use:
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