Last update Dec. 21, 2022

Valacyclovir Hydrochloride; Valaciclovir Hydrochloride

Very Low Risk

Safe. Compatible. Minimal risk for breastfeeding and infant.

It is a prodrug of Aciclovir which is used for treatment of infections due to Herpes zoster and Herpes simplex viruses and the prevention of Cytomegalovirus infection in immunocompromised patients. It decrease early breast milk and plasma HIV-1 RNA among women receiving prevention of mother-to-child transmission (Drake 2012 feb). Oral administration two to three times a day.

It is excreted into breast milk as Aciclovir in non-significant clinical amount (Drake 2012-7, Sheffield 2002), with no side-effects observed among breastfed infants from treated mothers. (Drake 2012-7)

Urine levels of Aciclovir in those infants were shown to be very low. (Sheffield 2002)

Several medical societies and expert authors consider the use of this medication safe while breastfeeding. (LactMed, Hale, OTIS 2022, Briggs 2015, Schaefer 2015, Butler 2014, Mactal 2001)


We do not have alternatives for Valacyclovir Hydrochloride; Valaciclovir Hydrochloride since it is relatively safe.

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

Valacyclovir Hydrochloride; Valaciclovir Hydrochloride is also known as

Valacyclovir Hydrochloride; Valaciclovir Hydrochloride in other languages or writings:


Valacyclovir Hydrochloride; Valaciclovir Hydrochloride belongs to this group or family:


Variable Value Unit
Oral Bioavail. 54 %
Molecular weight 324 daltons
Protein Binding 15 %
Tmax 1 - 2 hours
3 hours
M/P ratio 0.6 - 4 -
Theoretical Dose 0.023 - 1.5 mg/Kg/d
Relative Dose 0.05 - 8 %
Ped.Relat.Dose 0.004 - 2.5 %


  1. LactMed. Drugs and Lactation Database (LactMed). Internet. Bethesda (MD): National Library of Medicine (US); 2006-. Available from: 2006 - Consulted on April 16, 2024 Full text (link to original source)
  2. Hale TW. Medications & Mothers' Milk. 1991- . Springer Publishing Company. Available from Consulted on April 10, 2024 Full text (link to original source)
  3. OTIS. Acyclovir (Zovirax®) / Valacyclovir (Valtrex®). 2022 Apr. Mother To Baby | Fact Sheets [Internet]. Brentwood (TN): Organization of Teratology Information Specialists (OTIS); 1994-. Consulted on April 21, 2022 Abstract
  4. Briggs GG, Freeman RK, Towers CV, Forinash AB. Drugs in Pregnancy and Lactation: A Reference Guide to Fetal and Neonatal Risk. Wolters Kluwer Health. Tenth edition (acces on line) 2015
  5. Schaefer C, Peters P, Miller RK. Drugs During Pregnancy and Lactation. Treatment options and risk assessment. Elsevier, Third Edition. 2015
  6. Butler DC, Heller MM, Murase JE. Safety of dermatologic medications in pregnancy and lactation: Part II. Lactation. J Am Acad Dermatol. 2014 Mar;70(3):417.e1-10; quiz 427. Abstract
  7. GSK. Valacyclovir. Drug Summary 2013 Full text (in our servers)
  8. Drake AL, Roxby AC, Kiarie J, Richardson BA, Wald A, John-Stewart G, Farquhar C. Infant safety during and after maternal valacyclovir therapy in conjunction with antiretroviral HIV-1 prophylaxis in a randomized clinical trial. PLoS One. 2012;7(4):e34635. Abstract Full text (link to original source) Full text (in our servers)
  9. Drake AL, Roxby AC, Ongecha-Owuor F, Kiarie J, John-Stewart G, Wald A, Richardson BA, Hitti J, Overbaugh J, Emery S, Farquhar C. Valacyclovir suppressive therapy reduces plasma and breast milk HIV-1 RNA levels during pregnancy and postpartum: a randomized trial. J Infect Dis. 2012 Feb 1;205(3):366-75. Abstract Full text (link to original source) Full text (in our servers)
  10. Valaciclovir. Ficha técnica. 2010 Full text (in our servers)
  11. Sheffield JS, Fish DN, Hollier LM, Cadematori S, Nobles BJ, Wendel GD Jr. Acyclovir concentrations in human breast milk after valaciclovir administration. Am J Obstet Gynecol. 2002 Abstract
  12. 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

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