Is Nirmatrelvir safe while breastfeeding?
Here is what NIH LactMed, the U.S. National Library of Medicine's authority on medicines and breastfeeding, reports about Nirmatrelvir. This is a summary of that source — not our own verdict.
Effects on the breastfed infant
In a cross-sectional study of women who had COVID-19 and received nirmatrelvir in combination ritonavir, two women breastfed their infants. No adverse effects were reported in the infants.[ 5 ]
Effects on milk supply
Relevant published information was not found as of the revision date.
Levels in milk
Maternal Levels. Eight women who were taking nirmatrelvir-ritonavir and had donated milk samples to a breastmilk repository had their milk analyzed for nirmatrelvir. All were taking a nirmatrelvir dose of 300 mg twice daily and reported taking milk samples at 0, 1, 2, 4, 6, 8, 10, and 12 hours after a dose. The peak nirmatrelvir concentration in milk occurred at 4 hours after the dose was 1107 mcg/L and the average concentration was 729 mcg/L. This translated into a daily infant dose of 0.108 mg/kg or a relative infant dose of 1.4%.[ 3 ] Eight healthy lactating women who were at least 12 weeks postpartum were administered 3 oral doses of 300 mg of nirmatrelvir and 100 mg of ritonavir every 12 hours. The peak nirmatrelvir concentration of 1.904 ng/L occurred at 3.22 hours and its mean half-life in breastmilk was 4.4 hours. The mean daily amounts of nirmatrelvir and ritonavir recovered in breastmilk were 0.752 mg and 0.027 mg, respectively, representing 0.13% and 0.014% of the corresponding administered daily maternal doses (unadjusted for weight). The estimated daily infant dosages (assuming average milk consumption of 150 mL/kg/day), were 0.16 mg/kg and 0.006 mg/kg or 1.8% and 0.19% of the maternal dose, respectively, for nirmatrelvir and ritonavir.[ 4 ] Infant Levels. Relevant published information was not found as of the revision date.
Source: NIH LactMed (National Library of Medicine).
Educational summary of an authoritative source — not medical advice. Never start, stop, or change a medicine while breastfeeding without confirming with your doctor.