Is Tamiflu safe while breastfeeding?

What does the evidence say about Tamiflu while breastfeeding?

1. Limited data indicate oseltamivir and its active metabolite are poorly excreted into breast milk. After a single 75 mg dose, peak milk levels averaged 26.9 mcg/L for oseltamivir at 3.4 hours and 41.9 mcg/L for the carboxylate metabolite at 18.9 hours. 1
2. At standard dosing the calculated infant exposure is about 0.9 mcg/kg of oseltamivir and 3.6 mcg/kg of the metabolite daily, far below the 3 mg/kg daily dose reported for infants. An initial case report put the worst-case infant dose at 0.012 mg/kg daily, or 0.5 percent of the mother's weight-adjusted dosage. 1
3. A pharmacokinetic study found breast milk levels of both the prodrug and the active metabolite were lower than plasma levels, with infants calculated to receive 2.1 micrograms per day, or 0.76 micrograms per kilogram per day, against a therapeutic infant dose of 1 to 7 mg/kg/day. 2
4. Taking an antiviral within 48 hours of the first symptoms, the earlier the better, can lower the chance of severe complications from the flu, and oseltamivir passes into breast milk in small amounts without reported side effects in nursing babies. 3
5. Vaccination alongside breastfeeding lowers infant risk substantially: combining prenatal vaccination with breastfeeding can reduce the chance of a baby getting influenza by up to 60 percent, and women who are breastfeeding can receive the flu shot. 4

How Tamiflu changes by nursing stage

• Early weeks. Newborn weeks, when a confirmed case of flu in the household is most frightening. The timing rule matters more than the milk numbers here: taking an antiviral within 48 hours of your first symptoms, the earlier the better, lowers the chance of severe complications.
• Established nursing. Established feeding. This is the stage where people ask whether to stop nursing while sick. LactMed found no published information on effects in breastfed infants, and the calculated exposure sits well under a therapeutic infant dose, which is why continuing is the usual advice.
• Weaning. Older baby, more direct contact and fewer feeds. The milk figures do not change with baby's age. What does change is that older infants may be candidates for their own care, which is a conversation for their pediatric clinician rather than an inference from your dose.