DOACs and interacting medicines: apixaban, rivaroxaban and what to check

The NHS describes rivaroxaban, apixaban and edoxaban as direct oral anticoagulants, with dabigatran also in the group, all taken as tablets or capsules. They are prescribed to prevent clots in conditions such as atrial fibrillation and after a clot in a leg or lung. Warfarin is the older tablet anticoagulant.

DOACs are given in fixed doses without routine INR testing, which suits many people. The trade-off is that a hidden interaction will not show up on a regular blood test, so prescribers and patients rely more on checking each new medicine.

Some combinations simply add bleeding risk because both products affect clotting or the stomach lining. The NHS apixaban and rivaroxaban pages list other anticoagulants such as warfarin, SSRI antidepressants and NSAID painkillers or anti-inflammatories. The NHS clopidogrel page adds that aspirin 300 mg tablets for pain relief or ibuprofen should not be taken unless a doctor says so.

Paracetamol is generally the painkiller people are steered towards when an NSAID is unsuitable; the NHS clopidogrel page calls it a safe alternative in that context. Ask a pharmacist for advice on your own combination before buying a painkiller.

• Other anticoagulants and antiplatelets.

• NSAIDs such as ibuprofen and, for pain relief, aspirin.

• SSRI antidepressants.

Antifungal medicines, some medicines for high blood pressure, heart problems or an irregular heartbeat, HIV medicines such as ritonavir, some antibiotics and epilepsy medicines can raise or lower DOAC levels. If levels rise, the bleeding risk increases; if they fall, clot protection weakens.

The NHS fluconazole page lists dabigatran, warfarin and clopidogrel among medicines to check, showing that the interaction works in both directions. Our enzyme-inducing medicines guide explains why rifampicin, carbamazepine and St John's wort are a particular concern.

The NHS names St John's wort in both the apixaban and rivaroxaban interaction lists. Because it can lower the level of some anticoagulants, a loss of protection against clots is the concern. People often buy it for low mood without realising it is a medicine in its own right.

The NHS herbal medicines page advises always checking with a pharmacist before taking a herbal medicine if you already take other medicine, and mentions blood thinners among the prescriptions affected.

The NHS says to tell your doctor or surgeon you take an anticoagulant before any procedure, because it may need to be stopped for a short time. Dental work counts. Do not stop the tablet yourself; the stopping and restarting plan should come from the team.

Showing the alert card to every clinician is a simple safety step, including in A&E and when a new prescriber sees you.

The NHS lists blood in urine or stools, black stools, nosebleeds, bleeding gums, coughing up blood, unusual bruising and heavy periods as signs of bleeding, and says to seek urgent help through NHS 111 for any bleeding symptoms or after a head injury. Call 999 for suspected bleeding inside the head, for example a sudden severe headache with confusion, or for anaphylaxis.