From the Guidelines
For toenail fungus, fluconazole should be prescribed at a dose of 450 mg once weekly for at least 6 months. This dosing regimen is based on the pharmacokinetic properties of fluconazole, which has a long half-life allowing for once-weekly dosing, and its efficacy in treating onychomycosis, as reported in the British Association of Dermatologists' guidelines for the management of onychomycosis 2014 1. The guidelines suggest that higher doses (450 mg per week) and longer treatment duration (9 and 12 months) are associated with higher cure rates, with mycological cure rates ranging from 47% to 62% in toenail infections.
When prescribing fluconazole, it is essential to consider the potential side effects, which include headache, skin rash, gastrointestinal complaints, and insomnia, and may lead to treatment discontinuation in up to 58% of patients receiving higher weekly doses (300–450 mg) 1. Additionally, fluconazole is a weaker inhibitor of the cytochrome P450 enzymes than itraconazole, which may result in fewer drug interactions.
To ensure the best possible outcome, patients should be advised to take fluconazole consistently on the same day each week, with or without food, and to maintain good nail hygiene, including keeping nails clean, dry, and trimmed short, wearing breathable footwear, and completing the full treatment course even if improvement is seen early on. Liver function tests may also be monitored during long-term treatment. It is crucial to note that fluconazole may be less effective than itraconazole or terbinafine, but its once-weekly dosing regimen may improve compliance in some patients, making it a useful alternative in patients unable to tolerate other treatments 1.
From the Research
Fluconazole Dose Instructions for Toe Nail Fungus
- The recommended dose of fluconazole for the treatment of distal subungual onychomycosis of the toenail is 150-450 mg once weekly 2, 3.
- The treatment duration can range from 6 to 12 months, with a mean time to clinical success of 6 to 7 months 2.
- A study found that fluconazole doses between 150 to 450 mg weekly for 6 months were clinically and mycologically effective as well as safe and well tolerated 2.
- Another study recommended a dosage of 300 mg once weekly and 300-450 mg once weekly (if molds are the offending agents) for better disease outcome, especially in cases of foot nail infections 4.
- The clinical and mycologic responses of the 9-month treatment duration were significantly superior to the 4- and 6-month durations 3.
- Fluconazole has been shown to be effective in eradicating clinical and mycologic symptoms of onychomycosis, with clinical success rates ranging from 86% to 100% 2, 5.
- The drug is generally well tolerated, with adverse events similar to those of placebo 2, 3, 5.