A 70-year-old client on chronic warfarin for atrial fibrillation and simvastatin 40 mg every evening is diagnosed with oral candidiasis after antibiotic therapy. The provider is considering oral fluconazole 200 mg daily. Which is the most appropriate nursing action?

Fluconazole (Diflucan) is a triazole antifungal active against Candida and some other yeasts and dermatophytes. It is a moderate to strong inhibitor of CYP2C9, CYP3A4, and CYP2C19, and prolongs QT. The combination with warfarin (CYP2C9 substrate) significantly raises INR and bleeding risk, with documented major hemorrhage. With simvastatin (CYP3A4 substrate) the rise in plasma level meaningfully increases myopathy and rhabdomyolysis risk. Patients also receive QT-prolonging fluoroquinolones, ondansetron, antiarrhythmics, antipsychotics — stacking risk. Standard nursing/care-coordination: (1) communicate with the prescriber and pharmacist; (2) for oral candidiasis, consider topical alternatives first — nystatin swish-and-swallow 4 to 6 mL QID or clotrimazole 10 mg troches five times daily — as effective for many uncomplicated cases without the systemic interactions; (3) if fluconazole is needed (severe or unresponsive disease, immunocompromised), anticipate INR check at baseline and within 3 to 5 days, possible warfarin dose reduction; statin hold during therapy or switch to rosuvastatin/pravastatin/pitavastatin; baseline ECG and electrolytes; (4) review home meds for QT or CYP cluster; (5) standard fluconazole monitoring — hepatotoxicity, GI, headache, rash including SJS, alopecia at high prolonged doses; (6) document allergies and patient education. Increasing warfarin, adding another statin, or administering without checks are unsafe.

Fluconazole stacks with warfarin and simvastatin and prolongs QT. Try topical nystatin or clotrimazole first; if systemic, communicate, monitor INR/CK, and consider statin switch.