Limited information indicates that oral maternal doses of 500 mg daily produce low levels in milk and would not be expected to cause any adverse effects in breastfed infants, especially if the infant is older than 2 months. Monitor the infant for jaundice or other signs of liver toxicity, especially in younger, exclusively breastfed infants. Some sources recommend avoiding oral terbinafine during nursing.[1]
Topical terbinafine has not been studied during breastfeeding. Because only about 1% is absorbed after topical application, it is considered a low risk to the nursing infant.[1][2] Avoid application to the nipple area and ensure that the infant's skin does not come into direct contact with the areas of skin that have been treated. Only water-miscible cream, gel or liquid products should be applied to the breast because ointments may expose the infant to high levels of mineral paraffins via licking.[3]