Emily Oster

2 min Read Emily Oster

Emily Oster

Can I Breastfeed on Paxlovid?

Q&A on safety

Emily Oster

2 min Read

Breastfeeding mom with COVID here. I have been prescribed Paxlovid and was told that I can’t breastfeed for the duration of the five-day treatment and for seven days thereafter. It seems to my untrained eye that the available data is mixed on Paxlovid while nursing, and am curious if your team has looked into it. 

—Pumping and Dumping for 12 Days Will Hurt My Soul

I’m sorry you have COVID, and I hope you are feeling okay!

The available data on Paxlovid in lactation (or pregnancy) is extremely limited. The original trials for Paxlovid did not include pregnant or breastfeeding women, which leaves doctors without something concrete to rest conclusions on. 

Having said that, there are two reasons your doctor’s guidelines seem like they might be too conservative. 

a parent and a child laying sidewise on a bed
William Fortunato / Pexels

First: the most recent NIH guidelines say that breastfeeding can be continued on Paxlovid. These guidelines acknowledge that data is limited. But based on animal studies and a very small amount of human data, they conclude that the amount of the antiviral that passes through to milk is likely negligible. As a result, it would be unlikely to create problems even if we were worried about infants having these antivirals directly.

Second: the half-life of Paxlovid (meaning the amount of time that it takes the concentration in your bloodstream to decline by half) is about six hours. Generally, we think of a medication as being (for practical purposes) fully eliminated within four to five half-lives, or something like 30 hours. This suggests that even if you wanted to completely eliminate the chance of infant exposure to the medication, that would be accomplished by waiting just about one day after you completed the course of treatment. 

I wish I could say that I thought we would have better data on this going forward, but I’m guessing we will not. Guidelines for Paxlovid prescribing at this point focus on individuals who are at risk for progression to severe disease. Most breastfeeding women do not fall into this category, meaning without a lot of very convincing data showing no risk, there will be reluctance to prescribe it widely. 

For now: at a minimum, I’d come back to your doctor with the NIH guidelines and the half-life and get their thoughts.

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