Lactation Safety Information
Moderate amount of published evidence shows negligible levels of ritonavir in breast milk resulting in variable infant serum levels, ranging from undetectable to low. No adverse effects reported in breastfed infants to date.
No published evidence for the excretion of nirmatrelvir into breast milk, but it is likely to pass into breast milk in very low amounts due to its favourable pharmacokinetics.
Paxlovid is administered as a short course, and nirmatrelvir and ritonavir both have a short half-life, so risk of accumulation in the infant is very low.
Two case reports in which nirmatrelvir/ritonavir was given to breastfeeding women did not report any adverse effects in their infants.
The manufacturer advises that breastfeeding is not recommended during treatment with nirmatrelvir/ritonavir and for 7 days after the last dose. This is to ensure any infant exposure via breast milk is completely avoided. However, this is not considered necessary.
As a precaution monitor infant for poor feeding, adequate weight gain, vomiting, diarrhoea, poor sleeping, and signs of jaundice.
Breastfeeding can continue during COVID-19 infection.
Further advice is available from the UK Drugs in Lactation Advisory Service .
22 June 2023