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Flecainide use while Breastfeeding

Medically reviewed by Last updated on Nov 14, 2022.

Drugs containing Flecainide: Tambocor

Flecainide Levels and Effects while Breastfeeding

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 flecainide 100 mg twice daily orally, milk flecainide levels were 0.89 and 1.09 mg/L at 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 flecainide 100 mg twice daily orally (average 3.2 mg/kg daily) for 5.5 days after delivery. Flecainide levels in 24-hour pooled milk samples averaged 0.756 mg/L (range 0.13 to 1.53 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.

Effects on Lactation and Breastmilk

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


Wagner X, Jouglard J, Moulin M, et al. Coadministration of flecainide acetate and sotalol during pregnancy: Lack of teratogenic effects, passage across the placenta, and excretion in human breast milk. Am Heart J. 1990;119:700–2. [PubMed: 1689933]
McQuinn RL, Pisani A, Wafa S, et al. Flecainide excretion in human breast milk. Clin Pharmacol Ther. 1990;48:262–7. [PubMed: 2119270]

Substance Identification

Substance Name


CAS Registry Number


Drug Class

Breast Feeding



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Further information

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