How long after finishing Paxlovid is it safe to breastfeed?

[mayab]

Dear InfantRisk,

I am finding conflicting information on when to resume breastfeeding my ten-months old baby after taking the last dose of Paxlovid. Could you please help me with what you think is the most reasonable waiting time based on your (and any available) research? Thank you, maya

[admin]

I don't think you really need to wait much at all. We have many women who are using this drug and simultaneously breastfeeding. We've not received any indication of problems for the infant.

At present there is no data on the transfer of Paxlovid combination product into human milk. Nirmatrelvir probably transfers into milk but we do not think it would be a problem in an infant.
Due to modest protein binding and molecular weight, nirmatrelvir is only expected to transfer into milk to a moderate degree. A transient small decrease in body weight (<10%) was observed in the nursing offspring of rats administered nirmatrelvir at doses 8 times higher than human equivalents. While it is not ideal for a breastfeeding mother, it is likely the benefit of treatment against COVID-19 may outweigh the infant risk of drug transfer with a short duration of therapy. Ritonavir is used to boost concentrations of nirmatrelvir. Ritonavir has been studied in breastfeeding mothers. It has moderate transfer into milk and low serum concentrations in some infants, but no reported adverse effects. Please refer to the ritonavir monograph for detailed information.

Tom Hale

[mayab]

Dear Dr Hale,

Thank you so much for your response. You helped me make the decision to continue to breastfeed my baby after I was considering moving to formula completely. This website is an amazing research-based resource for nursing moms!

Thanks again,
maya