There are very limited data on the excretion of fluconazole in breast milk.
Fluconazole, after a 200 mg oral dose, produces levels in breast milk similar to those found in maternal plasma.
Fluconazole is recommended for use in the treatment of neonates with fungal infections at a dose starting at 3 mg/kg every 72 hours. The calculated dose of fluconazole ingested by an infant feeding at times of peak milk levels of fluconazole would be approximately 0.6 mg/kg/day, which is 60% of the neonatal dose and 20% of the dose for infants aged one month and over.
Fluconazole is often used to treat lactation-associated candidal infections, and has been used to treat serious candidal infections in preterm and full term neonates. There is therefore clinical experience in the exposure of fluconazole to neonates and infants
The combination of these factors, and the common use of fluconazole without reported adverse effects in breastfed infants, suggests that oral fluconazole is safe in mothers breastfeeding full term infants, and no interruption of breastfeeding is necessary, regardless of which dosing regime is used.
Oral fluconazole use in mothers breastfeeding preterm infants should be approached with caution due to no direct evidence of safety and limited clinical experience.
Senior Medicines Information Pharmacist, Trent & West Midlands Medicines Information Services, UK Drugs in Lactation Information Service