Attribution Statement: LactMed is a registered trademark of the U.S. Department of Health and Human Services.
NCBI Bookshelf. A service of the National Library of Medicine, National Institutes of Health.
Drugs and Lactation Database (LactMed®) [Internet]. Bethesda (MD): National Institute of Child Health and Human Development; 2006-.
CASRN: 124832-27-5

Drug Levels and Effects
Summary of Use during Lactation
The dosage of acyclovir in milk after valacyclovir is less than 1% of a typical infant dosage and would not be expected to cause any adverse effects in breastfed infants. No special precautions are required when using valacyclovir during breastfeeding. In one study, administration of valacyclovir to mothers with concurrent herpes simplex type 2 and HIV infections reduced breastmilk shedding of the HIV virus in breastmilk at 6 and 14 weeks postpartum, but not later.[1] In another study in HIV-positive mothers, valacyclovir did not reduced breastmilk shedding of cytomegalovirus (CMV) or infant CMV acquisition.[2]
Drug Levels
Valacyclovir is a prodrug that is rapidly converted to acyclovir in the body.
Maternal Levels. Five mothers who were nursing neonates were given valacyclovir 500 mg orally every 12 hours for 5 days. Valacyclovir was not detected in milk. Median peak acyclovir concentrations in milk of 4.2 mg/L occurred at 2 to 4 hours after the first dose and was similar after the last dose. The authors calculated the median milk concentration at steady-state to be 2.24 mg/L. The median half-life in milk was 2.1 hours (range 1.3 to 12.2 hours).[3] Using the median milk levels from this study, an exclusively breastfed infant would receive 0.34 mg/kg daily by mouth with this regimen, which is less than 1% of dosage given to neonates.
In a study of pregnant women with concurrent HIV and Herpes simplex infections, mothers received zidovudine 300 mg daily from week of pregnancy until 12 months postpartum and nevirapine at delivery. Half of the women (n = 74) also received valacyclovir 500 mg orally twice daily from 34 weeks gestation until 12 months postpartum. Milk samples (timing not stated) from 44 women obtained at 2 weeks postpartum found detectable acyclovir in 35 samples, with a median concentration of 2.6 mg/L (range 0.15 to 10.15 mg/L) Three of the 9 women with undetectable milk acyclovir levels had missed one or more doses of valacyclovir in the previous 2 days.[4]
Infant Levels. The urine of 5 infants whose mothers were taking valacyclovir 500 mg every 12 hours orally was collected. Valacyclovir was not detected in any of the infant's urine. The median infant urine acyclovir concentration on day 5 of therapy was 0.74 mg/L.[3]
Effects in Breastfed Infants
In a study of pregnant women with concurrent HIV and Herpes simplex infections, mothers received zidovudine 300 mg daily from week of pregnancy until 12 months postpartum and nevirapine at delivery. Half of the women (n = 74) also received valacyclovir 500 mg orally twice daily from 34 weeks gestation until 12 months postpartum. At 6 weeks postpartum, all infants who received acyclovir in breastmilk had normal serum creatinine (<0.83 mg/dL). Their median serum creatinine and alanine aminotransferase (ALT) values, and growth were no different from those of unexposed infants, with the exception of one infant with an ALT level of 70.1 units/L. Infants whose mothers received valacyclovir generally had adverse effects that were similar to the placebo group, except that treated infants had a lower risk of eczema and oral thrush than infants in the placebo arm.[1][4]
Effects on Lactation and Breastmilk
Relevant published information was not found as of the revision date.
Alternate Drugs to Consider
References
- 1.
- Drake AL, Roxby AC, Ongecha-Owuor F et al. Valacyclovir suppressive therapy reduces plasma and breast milk HIV-1 RNA levels during pregnancy and postpartum: a randomized trial. J Infect Dis. 2012;205:366-75. [PMC free article: PMC3256951] [PubMed: 22147786]
- 2.
- Roxby AC, Atkinson C, Asbjornsdottir K et al. Maternal valacyclovir and infant cytomegalovirus acquisition: A randomized controlled trial among HIV-infected women. PLoS One. 2014;9:e87855. [PMC free article: PMC3913686] [PubMed: 24504006]
- 3.
- Sheffield JS, Fish DN, Hollier LM et al. Acyclovir concentrations in human breast milk after valaciclovir administration. Am J Obstet Gynecol. 2002;186:100-2. [PubMed: 11810093]
- 4.
- Drake AL, Roxby AC, Kiarie J et al. Infant safety during and after maternal valacyclovir therapy in conjunction with antiretroviral HIV-1 prophylaxis in a randomized clinical trial. PLoS One. 2012;7:e34635. [PMC free article: PMC3324503] [PubMed: 22509337]
Substance Identification
Substance Name
Valacyclovir
CAS Registry Number
124832-27-5
Drug Class
- Breast Feeding
- Anti-Infective Agents
- Antiviral Agents
Disclaimer: Information presented in this database is not meant as a substitute for professional judgment. You should consult your healthcare provider for breastfeeding advice related to your particular situation. The U.S. government does not warrant or assume any liability or responsibility for the accuracy or completeness of the information on this Site.
- User and Medical Advice Disclaimer
- LactMed App
- Drugs and Lactation Database (LactMed) - Record Format
- LactMed - Database Creation and Peer Review Process
- Fact Sheet. Drugs and Lactation Database (LactMed)
- Drugs and Lactation Database (LactMed) - Glossary
- LactMed Selected References
- Drugs and Lactation Database (LactMed) - About Dietary Supplements
- Breastfeeding Links
- PMCPubMed Central citations
- PubChem SubstanceRelated PubChem Substances
- PubMedLinks to PubMed
- Maternal valacyclovir and infant cytomegalovirus acquisition: a randomized controlled trial among HIV-infected women.[PLoS One. 2014]Maternal valacyclovir and infant cytomegalovirus acquisition: a randomized controlled trial among HIV-infected women.Roxby AC, Atkinson C, Asbjörnsdóttir K, Farquhar C, Kiarie JN, Drake AL, Wald A, Boeckh M, Richardson B, Emery V, et al. PLoS One. 2014; 9(2):e87855. Epub 2014 Feb 4.
- Review Acyclovir.[Drugs and Lactation Database (...]Review Acyclovir.. Drugs and Lactation Database (LactMed®). 2006
- Infant safety during and after maternal valacyclovir therapy in conjunction with antiretroviral HIV-1 prophylaxis in a randomized clinical trial.[PLoS One. 2012]Infant safety during and after maternal valacyclovir therapy in conjunction with antiretroviral HIV-1 prophylaxis in a randomized clinical trial.Drake AL, Roxby AC, Kiarie J, Richardson BA, Wald A, John-Stewart G, Farquhar C. PLoS One. 2012; 7(4):e34635. Epub 2012 Apr 11.
- A randomized, placebo-controlled comparison of oral valacyclovir and acyclovir in immunocompetent patients with recurrent genital herpes infections. The Valaciclovir International Study Group.[Arch Dermatol. 1998]A randomized, placebo-controlled comparison of oral valacyclovir and acyclovir in immunocompetent patients with recurrent genital herpes infections. The Valaciclovir International Study Group.Tyring SK, Douglas JM Jr, Corey L, Spruance SL, Esmann J. Arch Dermatol. 1998 Feb; 134(2):185-91.
- Review Valganciclovir.[Drugs and Lactation Database (...]Review Valganciclovir.. Drugs and Lactation Database (LactMed®). 2006
- Valacyclovir - Drugs and Lactation Database (LactMed®)Valacyclovir - Drugs and Lactation Database (LactMed®)
Your browsing activity is empty.
Activity recording is turned off.
See more...