Management of Dental Patients Taking Anticoagulants or Antiplatelet Drugs



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5 Treating a Patient Taking Warfarin or another Vitamin K Antagonist


Although the use of warfarin is well established, managing its therapeutic anticoagulation activity can be complicated. Due to substantial drug and dietary interactions, variation in patients’ responses to the drug and its narrow therapeutic range, warfarin activity has to be monitored frequently. This is achieved using the INR (International Normalised Ratio) test, which measures the time taken for a clot to form in a blood sample, relative to a standard. An INR value of 1 indicates a level of coagulation equivalent to that of an average patient not taking warfarin, and values greater than 1 indicate a longer clotting time and thus a longer bleeding time. The INR test is also used for patients taking the less commonly used VKAs, acenocoumarol and phenindione.

Target INR levels differ depending on the indication for which the drug is prescribed and can range from 2.5-3.5±0.5. A patient’s warfarin therapy will be adjusted by their medical practitioner or anticoagulation service (or by the patient if self-monitoring) as necessary to achieve the target INR level appropriate for their medical condition. Warfarinised patients will have a record of their INR test results, which they should present when attending for dental treatment.



Key Recommendation:

For a patient who is taking warfarin or another vitamin K antagonist, with an INR below 4, treat without interrupting their anticoagulant medication.

(Strong recommendation; low quality evidence)


This recommendation is based on the available evidence2,20-22 and extensive clinical experience. It should be considered a strong recommendation, because of emphasis placed on the potential risk of a thromboembolic event if warfarin treatment is interrupted. Further details on the development of the recommendations in this guidance can be found in Appendix 1 and at www.sdcep.org.uk.

For dental treatment that is likely to cause bleeding, with a low or higher risk of bleeding complications (see Table 1):

Ensure that the patient’s INR has been checked, ideally no more than 24 hours before the procedure. If the patient has a stable INRa, checking the INR no more than 72 hours before is acceptable.

If there is reason to believe that a test result obtained up to 72 hours before dental treatment may not reflect the current level, then the patient's INR should be tested again no more than 24 hours before the dental procedure.

If the patient’s INR is 4 or above, inform the patient’s general medical practitioner or anticoagulation service and delay treatmentb until the patient’s INR has been reduced to less than 4. For urgent treatment, refer the patient to secondary dental care.

If the patient’s INR is below 4, treat according to the general advice for managing bleeding risk (see Section 4), without interrupting their anticoagulant.

In addition:

Consider limiting the initial treatment area (e.g. perform a single extraction or limit subgingival periodontal scaling to 3 teeth, then assess bleeding before continuing).

For procedures with a higher risk of post-operative bleeding complications (see Table 1), consider carrying out the treatments in a staged manner over separate visits or seek advice from a more experienced colleague in primary or secondary dental care (see Section 3.1).

Use local haemostatic measures to achieve haemostasis. Actively consider suturing and packing, taking into account all relevant patient factors (see Section 4).



a Based on the BNF’s definition, a stable patient would be one who does not require weekly monitoring and who has not had any INR measurements above 4 in the last 2 months.19

b If the patient is prescribed amoxicillin for the dental condition, be aware that this may affect their INR level and that this should be checked 24 hours after starting the antibiotic.

6 Treating a Patient Taking an Antiplatelet Drug(s)


Patients taking antiplatelet medications tend to have prolonged bleeding times5, which is a consequence of the requirement for platelet aggregation in the formation of the initial platelet plug in primary haemostasis. This should be taken into consideration when planning dental treatments likely to cause bleeding, to ensure that sufficient time is available to achieve and monitor haemostasis.

There is no suitable test equivalent to the INR for measuring the antiplatelet effect of the various drugs that patients may be taking. Patients on dual antiplatelet therapies may have a higher risk of prolonged bleeding compared to those on a single antiplatelet drug and should be managed accordingly.

The most commonly encountered antiplatelet combination is aspirin with clopidogrel (for acute coronary syndrome). Dipyridamole with aspirin after a stroke or transient ischaemic attack (TIA) is less commonly prescribed, as clopidogrel monotherapy is considered to be more effective and better tolerated. The newer antiplatelet drugs prasugrel (Efient) and ticagrelor (Brilique) are only prescribed in combination with aspirin and are currently only licensed for patients with acute coronary syndrome.23,24 Evidence relating to bleeding risks with prasugrel and ticagrelor in the context of dental procedures is very limited.

Patients with a coronary artery stent will be prescribed dual antiplatelet therapy for up to 12 months. It is extremely important that this treatment is not stopped prematurely or interrupted without prior discussion and written advice from the patient’s cardiologist because of the risk of major adverse cardiac events.




Key Recommendation:

For a patient who is taking single or dual antiplatelet drugs, treat without interrupting their antiplatelet medication.

(Strong recommendation; low quality evidence)


This recommendation is based on the available evidence5,21,22,25 and extensive clinical experience. It should be considered a strong recommendation, because of emphasis placed on the potential risk of a thromboembolic event if antiplatelet treatment is interrupted. Further details on the development of the recommendations in this guidance can be found in Appendix 1 and at www.sdcep.org.uk.

For dental treatment that is likely to cause bleeding, with a low or higher risk of bleeding complications (see Table 1):

Treat the patient according to the general advice for managing bleeding risk (see Section 4), without interrupting their antiplatelet medication.



In addition:

If the patient is taking aspirin alone

Consider limiting the initial treatment area (e.g. perform a single extraction or limit subgingival periodontal scaling to 3 teeth, then assess bleeding before continuing).

For procedures with a higher risk of post-operative bleeding complications (see Table 1), consider carrying out the treatments in a staged manner over separate visits or seek advice from a more experienced colleague in primary or secondary dental care (see Section 3.1).

Use local haemostatic measures to achieve haemostasis.

If the patient is taking another single antiplatelet drug or dual antiplatelet drug

Be aware that bleeding may be prolonged (up to an hour). This should be taken into account when planning treatment time.

Limit the initial treatment area (e.g. perform a single extraction or limit subgingival periodontal scaling to 3 teeth, then assess bleeding before continuing).

For procedures with a higher risk of post-operative bleeding complications (see Table 1), consider carrying out the treatments in a staged manner over separate visits, or seek advice from a more experienced colleague in primary or secondary dental care (see Section 3.1).

Use local haemostatic measures to achieve haemostasis. Actively consider suturing and packing, taking into account all relevant patient factors (see Section 4).



Other drug combinations:

For some patients other combinations of medications are prescribed, including aspirin with warfarin or clopidogrel with warfarin or in rare cases, triple drug combinations. These patients are likely to have a higher bleeding risk and may have additional medical complications.



For a patient who is taking another combination of antiplatelet drugs and/or anticoagulants and requires dental treatment that is likely to cause bleeding, with a low or higher risk of bleeding complications (see Table 1):

Consult with the patient’s general medical practitioner or prescribing physician in order to assess the likely impact of the particular drug combination and the patient’s medical condition on their bleeding risk. If necessary seek advice from, or refer to, a more experienced colleague in primary or secondary dental care (see Section 3.1).




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