Bleeding Gums and an INR of 7.8 After a Urinary Tract Infection
You are the pharmacist on duty in a community pharmacy in Kano when a 72-year-old man presents with bleeding gums and fresh bruises on both forearms. He has atrial fibrillation and has taken warfarin 5 mg daily for three years; his last INR, two weeks ago, was 2.5. Ten days ago a private clinic prescribed co-trimoxazole 960 mg twice daily for seven days for a urinary tract infection. He also took diclofenac 50 mg three times daily for four days for back pain because 'the clinic did not give pain medicine.' He finished the antibiotic two days ago. Today he feels tired but has no black stools, no vomiting, and no headache. Blood pressure is 138/82 mmHg, pulse 88 beats/min and irregular. He lives alone and drove himself to the pharmacy. He asks whether he should just stop the warfarin for a few days. His next clinic appointment is in three weeks.
1. Explain the likely reasons for the bleeding and assess how urgent the situation is.
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Mechanism
- Co-trimoxazole contains sulfamethoxazole, which inhibits CYP2C9, a major enzyme responsible for metabolising warfarin. This can raise warfarin exposure and prolong the INR. Protein-binding displacement may add to the effect.
- Diclofenac adds two separate risks: NSAIDs inhibit platelet cyclo-oxygenase and impair platelet aggregation, and they can injure the gastric mucosa. Both increase bleeding risk in an already over-anticoagulated patient.
- The combination produced an INR of 7.8 with gum bleeding and bruising. This is not a trivial nuisance; it is over-anticoagulation with active minor bleeding and a real risk of major bleeding.
Urgency
He needs same-day medical assessment, not a three-week wait and not simply a self-directed warfarin holiday. Although he has no black stools, vomiting, or headache, absence of those signs does not exclude a serious bleed. His tiredness is nonspecific but should be taken seriously in an elderly patient living alone. He should not drive himself if he becomes dizzy or unwell; arrange transport or ask someone to accompany him.
2. What immediate advice and referral would you give, and what would you specifically avoid doing?
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Immediate actions
- Do not tell him to take another warfarin dose until he has been assessed. Advise him to hold the next dose and seek urgent medical review.
- Contact his clinic or the nearest emergency department and send a short referral note: current INR 7.8, warfarin 5 mg daily, recent co-trimoxazole, recent diclofenac, bleeding gums and bruising, no melena or haematemesis, blood pressure 138/82 mmHg.
- Check for red flags: black or bloody stools, blood in urine, severe headache, vomiting, abdominal pain, shortness of breath, fainting, or a fall. If any are present, arrange emergency transfer rather than a routine appointment.
- Advise him to avoid aspirin, ibuprofen, diclofenac, and other NSAIDs. For pain, paracetamol may be discussed with the clinician, but even that should be documented.
- Tell him not to start vitamin K, herbal remedies, or 'blood thinners' on his own.
What to avoid
Do not simply say 'stop the warfarin for a few days' and send him home; that is a clinical decision requiring assessment and monitoring. Do not give an NSAID for the back pain. Do not reassure him that the gum bleeding is harmless because the INR is only a laboratory number; the bleeding makes it clinically significant.
3. After he has been stabilised, what monitoring and counselling would you provide to reduce the chance of recurrence?
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Monitoring
- Arrange frequent INR checks during the recovery period, with the interval set by the anticoagulation service. Recheck after any new medicine is started or stopped.
- Ensure renal and liver function and haemoglobin are reviewed, especially after bleeding and NSAID exposure.
- Ask about bleeding symptoms at every contact: bruising, gum bleeding, nosebleeds, dark stools, blood in urine, and unusual headache.
Counselling
- Explain that warfarin interacts with many antibiotics and painkillers. He must tell every prescriber and pharmacist that he takes warfarin before accepting a new medicine.
- Give him a written anticoagulant alert card and encourage him to carry it.
- Advise a consistent, not excessive, intake of vitamin K-rich foods; sudden large changes in green vegetables can affect the INR.
- Limit alcohol and avoid starting herbal products without review.
- Reinforce bleeding precautions: soft toothbrush, electric razor, caution with knives and gardening, and prompt reporting of falls or head injury.
- Emphasise that the target INR is individualised; the fact that he felt well at INR 2.5 does not mean that a higher INR is safe.