Drug Levels and Effects:

Summary of Use during Lactation:

Limited information indicates that maternal doses of flecainide up to 200 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. Because of the relative lack of data concerning breastfeeding during maternal flecainide therapy, exclusively breastfed infants should be carefully monitored if this drug is used during lactation, possibly including measurement of serum levels to rule out toxicity if there is a concern.

Drug Levels:

Maternal Levels.

In one mother taking oral flecainide 100 mg twice daily, milk flecainide levels were 0.89 and 1.09 mg/L 3 hours after the mother's second dose of the day on days 5 and 7 postpartum, respectively.[1] Assuming the measured levels are approximately peak levels, the amounts in milk represent a maximum infant dosage of about 4.5% of the maternal weight-adjusted dosage.

Eleven healthy volunteer women were given oral flecainide 100 mg twice daily (average 3.2 mg/kg daily) for 5.5 days after delivery.Flecainidelevels in 24-hour pooled milk samples averaged 0.756 mg/L (range 0.134 to 1.529 mg/L) among the 11 women on day 5 when steady state had been attained. This corresponds to an average infant dosage of 3.6% (range 0.7 to 6.9%) of the maternal weight-adjusted dosage. After the last dose, the half-life of flecainide in breastmilk averaged 14.7 hours.[2]

Infant Levels.

Relevant published information was not found as of the revision date.

Effects in Breastfed Infants:

Relevant published information was not found as of the revision date.

Possible Effects on Lactation:

Relevant published information was not found as of the revision date.


1. Wagner X, Jouglard J, Moulin M et al. Coadministration offlecainideacetateand sotalol during pregnancy: lack of teratogenic effects, passage across the placenta, and excretion in human breast milk. Am Heart J. 1990;119:700-2. PMID:1689933
2. McQuinn RL, Pisani A, Wafa S et al.Flecainideexcretion in human breast milk. Clin Pharmacol Ther. 1990;48:262-7. PMID:2119270

Substance Identification:

Substance Name:


CAS Registry Number:


Drug Class:

  • Antiarrhythmics

  • Administrative Information:

    LactMed Record Number:


    Last Revision Date:

    Disclaimer:Information presented in this database is not meant as a substitute for professional judgment. You should consult your healthcare provider for breastfeeding advice related to your particular situation. The U.S. government does not warrant or assume any liability or responsibility for the accuracy or completeness of the information on this Site.