Is lamotrigine (Lamictal) safe for breastfeeding?

Lamotrigine Safety During Breastfeeding

Lamotrigine is generally safe for breastfeeding and can be continued in most circumstances, as the benefits of breastfeeding typically outweigh the relatively low risks of infant exposure to this medication.

Key Safety Evidence

Lamotrigine does transfer into breast milk at significant levels, but clinical experience demonstrates this is usually well-tolerated by infants:

• Breast milk concentrations average approximately 60-66% of maternal serum levels, with a mean milk-to-serum ratio of 0.66 1
• Estimated infant exposure ranges from 0.26-0.52 mg/kg/day depending on whether breastfeeding is partial or exclusive 1
• Despite measurable infant serum concentrations, serious adverse effects are rare 2, 3

Clinical Safety Data

Recent prospective studies support the safety of lamotrigine during lactation:

• In a study of 20 mother-infant pairs taking lamotrigine (mean dose 161 mg/day, range 50-400 mg/day), no serious adverse events occurred and 19 of 20 pairs successfully continued breastfeeding through one month postpartum 2
• Observed minor effects (drowsiness, rash, jaundice) were not significantly different from control groups and all infants recovered without intervention 2
• No neonatal withdrawal symptoms were documented 2

Important Considerations

Infant exposure through breast milk is substantially lower than in utero exposure:

• Neonatal lamotrigine serum concentrations are higher at birth (from placental transfer) than during lactation, meaning infants have already experienced greater exposure during pregnancy 4
• This context is important when counseling mothers who have taken lamotrigine throughout pregnancy 4

Maternal dose adjustments are critical in the postpartum period:

• Toxicity may occur more commonly in the mother rather than the infant if dose readjustments are not made gradually after delivery 4
• Therapeutic drug monitoring of maternal serum concentrations can predict infant exposure, as there is strong correlation between maternal serum levels and breast milk concentrations (Spearman's rho = 0.986) 1, 5

Practical Management Recommendations

For mothers wishing to breastfeed while taking lamotrigine:

• Breastfeeding can be initiated and maintained given the substantial benefits of breast milk 4
• Use the lowest effective maternal dose to minimize infant exposure while maintaining seizure control 5
• Monitor infants periodically for signs of drowsiness, poor feeding, or decreased alertness 3
• Consider therapeutic drug monitoring of maternal levels to optimize dosing and predict infant exposure 1, 5

Common Pitfalls to Avoid

• Do not automatically discontinue breastfeeding based solely on lamotrigine use—the evidence supports continuation in most cases 2, 3, 4
• Do not forget maternal dose adjustments in the postpartum period, as maternal toxicity is a greater concern than infant toxicity 4
• Do not overlook the context that infants have already experienced higher in utero exposure throughout pregnancy 4