Last update May 5, 2022


Low Risk

Possibly safe. Probably compatible. Mild risk possible. Follow up recommended. Read the Comment.

Nirmatrelvir is an antiviral protease inhibitor with emergency use authorization for the treatment of coronavirus disease 2019 (COVID-19) in adults who do not require supplemental oxygen delivery and who are at high risk for progression to severe COVID-19, including hospitalization or death (EMA 2022, FDA 2022). It is given together with Ritonavir to increase its bioavailability, which is low. (Mikus 2022)

At the date of the last update we did not find any published data on its excretion in breast milk.

Its pharmacokinetic data (very wide volume of distribution and moderately high molecular weight) make it highly unlikely that significant quantities will pass into breast milk.

Its low oral bioavailability minimizes the passage into plasma of the infant from ingested breast milk, except in the premature and in the immediate neonatal period in which there may be greater intestinal permeability.

Possible side effects are neither frequent nor serious. (EMA 2022, FDA 2022)

Expert authors consider the use of this medication possible during breastfeeding. (Anderson 2022)

See below the information of these related products:


  • Remdesivir ( Safe. Compatible. Minimal risk for breastfeeding and infant.)

Suggestions made at e-lactancia are done by APILAM team of health professionals, and are based on updated scientific publications. It is not intended to replace the relationship you have with your doctor but to compound it. The pharmaceutical industry contraindicates breastfeeding, mistakenly and without scientific reasons, in most of the drug data sheets.

Jose Maria Paricio, Founder & President of APILAM/e-Lactancia

Your contribution is essential for this service to continue to exist. We need the generosity of people like you who believe in the benefits of breastfeeding.

Thank you for helping to protect and promote breastfeeding.

José María Paricio, founder of e-lactancia.

Other names

Nirmatrelvir in other languages or writings:

  • PF-07321332 (Experimental code/s)
  • C23H32F3N5O4 (Molecular formula)


Nirmatrelvir belongs to this group or family:


Main tradenames from several countries containing Nirmatrelvir in its composition:

  • Paxlovid™. Contains other elements than Nirmatrelvir in its composition


Variable Value Unit
Oral Bioavail. < 20 %
Molecular weight 500 daltons
Protein Binding 69 %
VD 1.5 l/Kg
pKa 7.1 -
Tmax 3 hours
6.1 hours


  1. Mikus G, Foerster KI, Terstegen T, Vogt C, Said A, Schulz M, Haefeli WE. Oral Drugs Against COVID-19-Management of Drug Interactions With the Use of Nirmatrelvir/Ritonavir. Dtsch Arztebl Int. 2022 Apr 15;(Forthcoming). pii: arztebl.m2022.0152. Consulted on May 5, 2022 Abstract
  2. Anderson PO. COVID-19 Drugs and Breastfeeding Update. Breastfeed Med. 2022 Apr 6. Consulted on May 5, 2022 Abstract
  3. EMA. Paxlovid. Ficha técnica. 2022 Full text (in our servers)
  4. FDA. Paxlovid. Drug Summary. 2022 Full text (in our servers)

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