Dental Drug Interactions: A UK Reference

The most important rule: don’t stop the anticoagulant

For the overwhelming majority of patients on warfarin, a DOAC, aspirin or clopidogrel, the correct action for routine dental treatment — including most extractions — is to continue the medication and control bleeding locally. Interrupting anticoagulation to "make the extraction safer" exposes the patient to thromboembolism (stroke, MI, stent thrombosis), which is a far greater risk than a manageable post-extraction bleed. Stopping or altering an anticoagulant/antiplatelet is a prescriber-and-specialist decision, not a routine dental one.

Local haemostatic measures for at-risk patients: atraumatic technique, sutures, oxidised cellulose or other haemostatic packing, and pressure. SDCEP does not advise primary care practitioners to prescribe tranexamic acid for dental procedures (it is not in the BNF List of Dental Preparations and is not available as a mouthwash); if the patient's medical practitioner has prescribed it, use it in addition to local measures.

Warfarin and dental treatment

Warfarin is a vitamin-K-antagonist anticoagulant; bleeding risk during and after dental procedures is increased and is monitored by INR.

• Check the INR ideally within 24 hours before invasive treatment (up to 72 hours if the patient is stably anticoagulated).
• INR below 4: treat without interrupting warfarin. INR 4 or above: delay invasive treatment or refer if urgent (SDCEP 2022).
• Do NOT stop warfarin — risk of thromboembolism.
• Use local haemostatic measures (sutures, oxidised cellulose, pressure).

Local anaesthetic: use an aspirating syringe and LA with a vasoconstrictor unless contraindicated. Infiltration, intraligamentary or mental nerve block is preferred over regional nerve blocks, whether or not the patient takes an anticoagulant. There is no evidence that an inferior dental block poses a significant bleeding risk in an anticoagulated patient; on warfarin, if there are signs of an unstable INR or other signs of excessive anticoagulation, request an INR before the procedure and proceed only if it is below 4 (SDCEP 2022, Table 1).

Analgesics: AVOID NSAIDs and aspirin — they potentiate the anticoagulant effect (and add GI bleeding risk). Paracetamol is safe. Codeine-based analgesics are acceptable short-term.

Antibiotics — the metronidazole/clarithromycin INR trap: do not prescribe metronidazole or clarithromycin to a patient taking warfarin (SDCEP), nor erythromycin, which the SDCEP Drug Prescribing for Dentistry drug-interactions entry for macrolide antibiotics (e.g. clarithromycin) also covers; metronidazole notably increases the anticoagulant effect. Azithromycin is different: SDCEP’s 2026 endocarditis advice says clarithromycin or azithromycin are suitable alternatives in penicillin allergy and restricts only clarithromycin with warfarin. Azithromycin and other antibiotics, including amoxicillin and phenoxymethylpenicillin, can raise the INR in a minority of patients: if you prescribe one, warn the patient that their INR may rise and inform their GP or anticoagulation service so extra INR monitoring can be considered (SDCEP Anticoagulants, Appendix 4). For phenoxymethylpenicillin or amoxicillin, SDCEP advises checking the INR 4–7 days after the course has started. Avoid miconazole oral gel (a clinically important antifungal interaction — use nystatin instead).

DOACs (apixaban, rivaroxaban, dabigatran, edoxaban) and dental extractions

DOACs (direct oral anticoagulants) need no INR monitoring, but bleeding risk is still increased and they should not be stopped without haematologist/specialist advice. For higher-bleeding-risk procedures, SDCEP advises timing the procedure around the dose rather than stopping the drug.

Across all DOACs: do NOT stop without specialist advice, use local haemostatic measures for any surgical procedure, prefer infiltration over nerve blocks, and for analgesia avoid NSAIDs — paracetamol is the analgesic of choice (codeine acceptable short-term).

Can I prescribe ibuprofen (or any NSAID) with warfarin or a DOAC?

No — avoid it. NSAIDs (including ibuprofen) and aspirin potentiate the anticoagulant effect and add gastrointestinal bleeding risk in patients on warfarin or a DOAC. Paracetamol is the safe first-line analgesic, and codeine-based analgesia is acceptable short-term if a stronger agent is needed. This applies to anticoagulants and antiplatelets generally — NSAIDs are the analgesic to avoid, not the one to reach for.

Statins and clarithromycin / erythromycin (the simvastatin contraindication)

This matters in dentistry because clarithromycin and erythromycin are the macrolide antibiotics reached for in penicillin allergy / second-line dental prescribing, and a large number of dental patients take a statin.

• Simvastatin is contraindicated with clarithromycin and erythromycin (potent CYP3A4 inhibitors) — co-administration markedly raises simvastatin exposure and the risk of myopathy and rhabdomyolysis (MHRA; BNF).
• Atorvastatin is also CYP3A4-metabolised; rosuvastatin and pravastatin are less affected. For dental prescribing, SDCEP does not separate them: do not prescribe clarithromycin to patients taking warfarin or statins.
• Practical dental point: before prescribing clarithromycin or erythromycin, check whether the patient takes a statin. If they do, do not prescribe clarithromycin or erythromycin (SDCEP); choose an alternative antibiotic or seek specialist advice.
• Azithromycin is an SDCEP 2026 alternative for endocarditis prophylaxis in penicillin allergy, and SDCEP restricts only clarithromycin with statins; its SmPC reports no change in atorvastatin exposure but advises caution because of post-marketing reports of rhabdomyolysis with statins.

SSRIs: dental considerations

SSRIs (fluoxetine, sertraline, citalopram, escitalopram — and related SNRIs) are very common, and the dental considerations are mostly about bleeding and analgesic/antibiotic choice.

• Increased bleeding risk due to impaired platelet aggregation (current BNF).
• Additive bleeding risk if combined with anticoagulants/antiplatelets — relevant when the SSRI patient is also on warfarin/a DOAC/aspirin.
• May cause xerostomia (dry mouth) — increased caries risk.
• Bruxism reported as a side effect — examine for tooth wear.
• Avoid tramadol and pethidine — serotonin syndrome risk.

Local anaesthetic: LA with adrenaline is safe; no special precautions. Analgesics: AVOID NSAIDs where possible (additive GI bleeding risk); paracetamol preferred; AVOID tramadol (serotonin syndrome). Antibiotics: Linezolid is contraindicated (serotonin syndrome). Standard dental antibiotics are safe.

Methotrexate

Methotrexate (low-dose weekly for rheumatoid arthritis / psoriasis, or higher-dose oncology) is immunosuppressive and has two prescribing traps that fall squarely in the dental domain.

• Immunosuppressed — increased infection risk.
• May cause oral ulceration and mucositis.
• Check FBC before invasive procedures (risk of pancytopenia).
• Delayed wound healing.

Local anaesthetic: LA with adrenaline is safe. Analgesics: AVOID NSAIDs — they reduce methotrexate excretion and cause toxicity. Paracetamol is safe. Antibiotics: Trimethoprim and co-trimoxazole are contraindicated (additive folate antagonism → myelosuppression). Penicillins such as amoxicillin can reduce methotrexate excretion (BNF interactions: risk of toxicity, monitor) — short dental courses are generally acceptable with caution; avoid prolonged courses and consider liaising with the prescriber. Metronidazole: no interaction listed in the BNF.

Quick reference: dental drug interactions at a glance

Verify every cell against the current BNF / DPF / SDCEP / MHRA before relying on it.

Check the patient’s medication in Nosht

This page gives you the reference and the principles. To check a specific patient's medication chairside, Nosht has an in-app Drug Interactions reference: a searchable reference covering commonly prescribed medications across anticoagulants/antiplatelets, antihypertensives, antidepressants, diabetes drugs, immunosuppressants, bisphosphonates/antiresorptives, steroids, antiepileptics and psychiatric medicines. For each drug it shows dental implications, LA considerations, analgesic considerations and antibiotic considerations, with a high/modify/low severity flag, and you can search by generic or brand name (e.g. Eliquis, Xarelto, Prozac, Tegretol). The reference is deterministic — it reads from a fixed, clinician-curated UK dental dataset and does not use a language model to generate clinical content (by design, for safety). It is a reference aid: the clinician verifies against the current BNF / SDCEP.

Both clinical tools sit inside the wider Nosht app. Nosht's note-writing features optionally use Anthropic's Claude Haiku 4.5, with clinician review, to help structure clinical notes from your input; the clinical reference tools above are deliberately deterministic and are not generated by AI.

Sources

• SDCEP: Management of Dental Patients Taking Anticoagulants or Antiplatelet Drugs, 2nd edition (2022) (accessed 11 October 2026)
• BNF interactions: Warfarin (accessed 11 October 2026)
• BNF interactions: Simvastatin (accessed 11 October 2026)
• SDCEP: Drug Prescribing for Dentistry (accessed 11 October 2026)
• SDCEP: Antibiotic prophylaxis (accessed 11 October 2026)