Last update May 23, 2019


Low Risk

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

Precursor of Penciclovir which is used for treatment of Herpes zoster infections and genital and mucocutaneous Herpes simplex (Novartis 2014, AEMPS 2010).
Oral administration in 2 - 3 daily doses.

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

Its pharmacokinetic data (low molecular weight and low percentage of plasma protein binding) makes it likely that significant amounts will pass into breast milk, although its large volume of distribution (Gill 1996) would make it difficult.

Its side effects are rare and mild (Mubareka 2010, Mactal 2001).

Possibly has low risk during breastfeeding because of having similar pharmacokinetics and side effects than other antivirals of the same family that are considered compatible with breastfeeding.

Until there is more published data on this drug in relation to breastfeeding, safer known alternatives may be preferable (Mactal 2001), especially during the neonatal period and in cases of prematurity


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

Famciclovir in other languages or writings:


Famciclovir belongs to these groups or families:


Main tradenames from several countries containing Famciclovir in its composition:


Variable Value Unit
Oral Bioavail. 60 - 77 %
Molecular weight 321 daltons
Protein Binding < 20 %
VD 1.1 ± 0.17 l/Kg
pKa 16.7 -
Tmax 1 hours
2 - 4 hours


  1. Novartis. Famciclovir Drug Summary. 2014 Full text (in our servers)
  2. AEMPS. Famciclovir. Ficha técnica. 2010 Full text (in our servers)
  3. Mubareka S, Leung V, Aoki FY, Vinh DC. Famciclovir: a focus on efficacy and safety. Expert Opin Drug Saf. 2010 Jul;9(4):643-58. Abstract
  4. 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
  5. Gill KS, Wood MJ. The clinical pharmacokinetics of famciclovir. Clin Pharmacokinet. 1996 Abstract
  6. Filer CW, Allen GD, Brown TA, Fowles SE, Hollis FJ, Mort EE, Prince WT, Ramji JV. Metabolic and pharmacokinetic studies following oral administration of 14C-famciclovir to healthy subjects. Xenobiotica. 1994 Abstract
  7. 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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