Some mothers develop fungal nail infections in pregnancy and delay treatment. When breastfeeding, topical treatments are preferable. I am asked at least once a week about oral terbinafine – hard to answer with little research. Hope this information helps with shared decision making.
Oral Terbinafine is sometimes used to treat fungal infection of the nails if topical products have failed to resolve symptoms. Treatment generally lasts for 3 months.
The most frequent adverse effects (for the mother) after oral use of terbinafine hydrochloride are gastrointestinal disturbances such as nausea, diarrhoea and mild abdominal pain. Loss or disturbance of taste may occur and occasionally may be severe enough to lead to anorexia and weight loss. Terbinafine hydrochloride is well absorbed from the gastrointestinal tract. The bioavailability is about 80% because of first-pass hepatic metabolism. Some people are unable to tolerate the drug because of side effects.
Oral terbinafine is extensively bound to plasma proteins (99%) so passage into breastmilk might be expected to be low. The only research refers to two women given a single dose of 500 mg; the total level of terbinafine measured in breastmilk during the 72-hour post-dosing period was 0.65 mg in one mother and 0.15 mg in another. Neither woman was breastfeeding, but both were producing some breastmilk (218 ml and 41 ml, respectively). After 18 hours, the levels of terbinafine were below the level of detection.
The volume of milk being produced by the mothers makes this study questionable as an evidence base. Similarly, the single dose does not replicate normal treatment. However, the authors suggested that using the average milk concentration values over the 24-hour period in the two subjects, an exclusively breastfed infant would receive 3.8% of the maternal weight-adjusted dosage of terbinafine.
Although unlicensed terbinafine has been used to treat tinea capitis in children (Gupta et al. 2003).
Skin concentrations may be up to 75-fold higher than those in the blood. It may persist in the skin for up to 8 weeks after the drug has been discontinued and in the nails for up to a year although treatment is stopped much sooner
The BNF reports that manufacturer advises avoidance of cream or tablets as it is present in milk but less than 5% of the dose is absorbed after topical application of terbinafine.
• Leachman SA, Reed BR, The use of dermatologic drugs in pregnancy and lactation, Dermatol Clin, 2006;24:167–97.
• Gupta AK, Adamiak A, Cooper EA, The efficacy and safety of terbinafine in children, J Eur Acad Dermatol Venereol, 2003;17:627–40.
• Thieme G, Peuckert U, Report on a pharmacokinetic study of SF 86-327 in healthy females in the ablactation period. Sandoz document number 303-019. 1986 (information taken from report in Lactmed and Hale 2017 online access).
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