Fluconazole Safety During Lactation

Fluconazole is safe to use during breastfeeding and mothers can continue nursing without interruption. 1

Guideline Recommendations

The strongest evidence supports fluconazole as the preferred azole antifungal for nursing mothers:

The Infectious Diseases Society of America (IDSA) explicitly recommends that breastfeeding mothers can safely continue nursing while taking fluconazole without any need to interrupt breastfeeding. 1
The American Academy of Pediatrics classifies fluconazole as "compatible" with breastfeeding, providing the highest level of guideline endorsement. 1
The European Respiratory Society/Thoracic Society of Australia and New Zealand task force confirms that fluconazole is present in breast milk but at levels less than the neonatal dosage, and that problems have not been observed in breastfed infants from mothers treated with oral fluconazole. 2

The reassuring safety profile is based on solid pharmacokinetic data:

After a single 150 mg dose, the estimated daily infant dose from breast milk is only 0.39 mg/kg/day, which represents approximately 13% of the recommended pediatric maintenance dose (3 mg/kg/day). 3
Peak milk concentrations occur at 5.2 hours post-dose, with mean levels of 2.61 mcg/mL. 3
Fluconazole has excellent oral bioavailability and is found in breast milk at concentrations comparable to blood levels, but the absolute amount transferred to the infant remains clinically insignificant. 4

Published clinical data further support safety:

A survey of 96 breastfeeding women treated with fluconazole 150 mg every other day (averaging 7.3 capsules) for lactation-associated candidiasis reported no serious adverse reactions in their infants. 3
Case reports document successful treatment of candidal mastitis and concurrent infant thrush using oral fluconazole in both mother and baby simultaneously, with relief of symptoms in both. 5
Clinical experience with higher doses (400 mg loading dose followed by 100 mg twice daily for 2 weeks) for persistent breast and nipple thrush shows no need to interrupt breastfeeding. 6

For common breastfeeding-related fungal infections:

Single doses of 150 mg are standard for vaginal candidiasis and are safe during lactation. 2, 7
For persistent breast/nipple thrush, higher doses (400 mg loading dose followed by 100-200 mg daily for 2+ weeks) can be used without interrupting breastfeeding. 6
The amount excreted in breast milk remains well below therapeutic infant doses even with maternal high-dose regimens. 3

A common pitfall is confusing pregnancy risks with lactation safety:

High-dose fluconazole (≥400 mg/day) during the first trimester of pregnancy is associated with congenital malformations (craniosynostosis, dysmorphic facies, cleft palate). 2, 3
This pregnancy concern does NOT apply to breastfeeding, where fluconazole is considered safe at all doses. 1
Even single 150 mg doses during first trimester pregnancy have been associated with possible increased miscarriage risk, but again, this is irrelevant to the lactation safety profile. 2

Fluconazole is the preferred systemic option:

Itraconazole, posaconazole, and voriconazole should be avoided during breastfeeding due to lack of safety data and potential toxicity concerns. 1, 8
Topical options (miconazole, nystatin) are "compatible" with breastfeeding for localized nipple infections, though excess cream should be removed before nursing. 1, 9
For systemic or persistent infections requiring oral therapy, fluconazole remains the clear first choice. 1

The safety in breastfed infants is reinforced by direct pediatric use:

Fluconazole is routinely used to treat fungal infections directly in infants as young as 1 day old, with doses ranging from 1-15 mg/kg/day. 3
The drug has a well-established safety profile in children, with efficacy demonstrated in treating oropharyngeal candidiasis in children 6 months to 13 years. 3
Since the infant exposure through breast milk (0.39 mg/kg/day) is far below direct therapeutic pediatric doses, the safety margin is substantial. 3