Last update: March 23, 2015


Very Low Risk for breastfeeding

Safe. Compatible.
Minimal risk for breastfeeding and infant.

Antiviral agent used for topical treatment of herpes of the lip. Famciclovir is its precursor drug which is used for systemic treatment.

At latest update, relevant published data on excretion into breast milk were not found.

After topical use, plasma levels are undetectable. Such property is the main reason by which it is not excreted into breast milk, In addition, a low oral bioavailability would impede the absorption from ingested milk toward the infant's plasma.

Do not apply creams, gels and other products for topical use that would contain paraffin (mineral oil) on the breast to prevent ingestion by the infant.

If necessary, apply Penciclovir after a feed and clean thoroughly with water before the next.


We do not have alternatives for Penciclovir since it is relatively safe.

Suggestions made at e-lactancia are done by APILAM´s pediatricians and pharmacists, and are based on updated scientific publications.
It is not intended to replace the relationship you have with your doctor but to compound it.

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.


Variable Value Unit
Oral Bioavail. 2 %
Molecular weight 237 daltons
Protein Binding 20 %
T1/2 2 hours


  1. FDA. Penciclovir. Drig Summary. 2013 Full text (in our servers)
  2. AEMPS. Penciclovir. Ficha técnica. 2011 Full text (in our servers)
  3. Concin N, Hofstetter G, Plattner B, Tomovski C, Fiselier K, Gerritzen K, Fessler S, Windbichler G, Zeimet A, Ulmer H, Siegl H, Rieger K, Concin H, Grob K. Mineral oil paraffins in human body fat and milk. Food Chem Toxicol. 2008 Abstract
  4. Noti A, Grob K, Biedermann M, Deiss U, Brüschweiler BJ. Exposure of babies to C15-C45 mineral paraffins from human milk and breast salves. Regul Toxicol Pharmacol. 2003 Abstract
  5. Mactal-Haaf C, Hoffman M, Kuchta A. Use of anti-infective agents during lactation, Part 3: Antivirals, antifungals, and urinary antiseptics. J Hum Lact. 2001 Abstract
  6. Pue MA, Pratt SK, Fairless AJ, Fowles S, Laroche J, Georgiou P, Prince W. Linear pharmacokinetics of penciclovir following administration of single oral doses of famciclovir 125, 250, 500 and 750 mg to healthy volunteers. J Antimicrob Chemother. 1994 Abstract

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e-lactancia is a resource recommended by Asociación Española de Bancos de Leche Humana from Spain

Would you like to recommend the use of e-lactancia? Write to us at corporate mail of APILAM