Is oral Lamisil (terbinafine) contraindicated during breastfeeding?

Oral Terbinafine (Lamisil) Use During Breastfeeding

Oral terbinafine (Lamisil) is contraindicated during breastfeeding as it is present in breast milk of nursing mothers with a milk-to-plasma ratio of 7:1, and treatment with terbinafine is not recommended in nursing mothers according to the FDA drug label. 1

Evidence on Terbinafine in Breastfeeding

• The FDA drug label for terbinafine explicitly states: "After oral administration, terbinafine is present in breast milk of nursing mothers. The ratio of terbinafine in milk to plasma is 7:1. Treatment with terbinafine is not recommended in nursing mothers." 1

• This high milk-to-plasma ratio (7:1) indicates significant concentration of the drug in breast milk, which could potentially expose the infant to considerable amounts of the medication. 1

Risk Assessment for Breastfed Infants

• Terbinafine undergoes extensive metabolism by at least seven CYP isoenzymes with major contributions from CYP2C9, CYP1A2, CYP3A4, CYP2C8, and CYP2C19, which may affect drug metabolism in infants who have immature enzyme systems. 1

• The drug has a terminal half-life of 200 to 400 hours in tissues such as skin and adipose, suggesting potential for accumulation with repeated exposure through breast milk. 1

• Unlike medications that are considered safe during breastfeeding (such as many antibiotics, local anesthetics, and analgesics like acetaminophen and ibuprofen), terbinafine carries a specific warning against use during lactation. 2, 3

Alternative Approaches

• When prescribing medications for breastfeeding patients, those with the lowest risk to the infant should be selected. 2

• For fungal infections requiring systemic treatment, consultation with a specialist may be needed to determine if:

  • Treatment can be delayed until after breastfeeding is completed 4
  • Topical antifungal therapy might be sufficient (as topical therapy generally limits infant exposure) 4
  • Alternative antifungal medications with better safety profiles during lactation could be used 3

Clinical Decision Making

• The benefits of medication use for the mother must be weighed against the potential risk of exposing the infant to medications through breast milk. 4

• In this case, the manufacturer's explicit contraindication and the high milk-to-plasma ratio strongly suggest avoiding oral terbinafine during breastfeeding. 1

• While most commonly used drugs are relatively safe for breastfed babies, terbinafine falls into the category of medications that should be avoided during lactation based on available evidence. 3

Common Pitfalls to Avoid

• Assuming that all oral antifungals have similar safety profiles in breastfeeding - they do not, and specific guidance for each medication should be followed. 3, 5

• Failing to consider the risk-benefit ratio - while fungal infections can be uncomfortable or even serious, alternative treatments or postponement of therapy should be considered when possible during breastfeeding. 4, 6

• Not consulting appropriate resources - using current, accurate resources like LactMed or pharmacy departments at maternity hospitals can provide up-to-date information on medication safety during breastfeeding. 2, 6