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. Note that the in-app tool lists tranexamic acid mouthwash; current SDCEP guidance does not routinely recommend it in primary dental care.

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 within 24–72 hours before invasive procedures.
• INR must be < 4 for extractions (ideally < 3.5).
• Do NOT stop warfarin — risk of thromboembolism.
• Use local haemostatic measures (sutures, oxidised cellulose, pressure).

Local anaesthetic: LA with adrenaline is safe. Use infiltration or mental/inferior dental block with care; avoid lingual and posterior superior alveolar nerve blocks at high INR (deep, poorly compressible sites).

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 macrolide/metronidazole INR trap: metronidazole, erythromycin and clarithromycin all potentiate warfarin (raise the INR). Amoxicillin can also raise the INR. Monitor INR if prescribing any antibiotic course longer than 5 days. 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. Per BNF/MHRA advice, simvastatin should be withheld during a course of clarithromycin or erythromycin (and for a short period afterwards).
• Atorvastatin is also CYP3A4-metabolised — use with caution / dose restriction with clarithromycin; avoid where possible.
• Rosuvastatin and pravastatin are not significantly CYP3A4-metabolised and are less affected — generally preferred where a macrolide cannot be avoided (a prescriber decision).
• Practical dental point: before prescribing clarithromycin or erythromycin, check whether the patient takes a statin; consider an alternative antibiotic, liaise with the GP, or note that the statin should be paused for the macrolide course.

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). Amoxicillin and metronidazole are safe.

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 decision-support: 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.

Do I stop warfarin before a dental extraction?

No — do not stop warfarin. For routine dental treatment, including most single and simple extractions, the patient continues warfarin and bleeding is controlled with local haemostatic measures (atraumatic technique, sutures, oxidised cellulose, pressure). Check the INR within 24–72 hours beforehand; it should be below 4 (ideally below 3.5) for extractions. Stopping warfarin risks thromboembolism, which outweighs the bleeding risk. Any change to anticoagulation is a prescriber/specialist decision. This is general guidance — verify against the current SDCEP anticoagulant guidance and BNF for the individual patient.

Can I prescribe ibuprofen with warfarin?

No — avoid ibuprofen and other NSAIDs (and aspirin) in patients on warfarin. NSAIDs potentiate the anticoagulant effect and add gastrointestinal bleeding risk. Paracetamol is the safe first-line analgesic, and codeine-based analgesia is acceptable short-term if needed. The same applies to patients on a DOAC or an antiplatelet.

Do DOACs need to be stopped for a dental extraction?

Usually not. DOACs (apixaban, rivaroxaban, dabigatran, edoxaban) need no INR monitoring and are generally continued, with bleeding managed locally. For higher-bleeding-risk procedures, SDCEP advises timing around the dose rather than stopping: for twice-daily apixaban, miss the morning dose and take it after haemostasis; for once-daily rivaroxaban/edoxaban, delay the dose and take it about 4 hours after haemostasis. Do not stop a DOAC without specialist/haematologist advice. Avoid NSAIDs; use paracetamol.

Which antibiotics interact with warfarin?

Metronidazole, erythromycin and clarithromycin all raise the INR, and amoxicillin can also raise it. If an antibiotic course is needed, prefer the lowest-risk option for the indication, monitor INR if the course is longer than 5 days, and avoid miconazole oral gel (use nystatin instead).

Can a patient on simvastatin take clarithromycin or erythromycin?

No — simvastatin is contraindicated with clarithromycin and erythromycin. These macrolides are potent CYP3A4 inhibitors and markedly increase simvastatin exposure, raising the risk of myopathy and rhabdomyolysis; BNF/MHRA advice is to withhold simvastatin during the macrolide course. Atorvastatin needs caution/dose restriction; rosuvastatin and pravastatin are less affected. Since clarithromycin/erythromycin are common second-line dental antibiotics, check statin therapy before prescribing a macrolide.

What are the dental considerations for a patient on an SSRI?

SSRIs increase bleeding risk (impaired platelet aggregation, per the current BNF), with additive risk alongside anticoagulants/antiplatelets. They commonly cause xerostomia (higher caries risk) and are associated with bruxism (check for tooth wear). For prescribing: avoid NSAIDs where possible, avoid tramadol and pethidine (serotonin syndrome), and paracetamol is preferred; linezolid is contraindicated. LA with adrenaline is safe.

What should I avoid prescribing to a patient on methotrexate?

Avoid NSAIDs (they reduce methotrexate excretion and cause toxicity) and avoid trimethoprim and co-trimoxazole (additive folate antagonism → myelosuppression). Paracetamol is safe; amoxicillin and metronidazole are safe. Methotrexate patients are immunosuppressed (increased infection risk), may have oral ulceration/mucositis, and an FBC should be checked before invasive procedures (pancytopenia risk).