Is Acyclovir compatible with breastfeeding? Do we have alternatives for Acyclovir?


December 9, 2017 (Very Low Risk)

Antiviral very active against herpes simplex and zoster-varicella.
Intravenous, oral and topical (dermatological and ophthalmological) administration.
Authorized use in newborns and infants.

It is excreted in breast milk in clinically insignificant amounts, much lower than the dose used in newborns and infants (Drake 2012, Bork 1995, Taddio 1994, Don 1991, Meyer 1988, Lau 1987), and no problems have been observed in infants whose mothers were taking acyclovir (Taddio 1994).

There is not systemic absorption of topical Acyclovir.

List of WHO essential medicines: compatible with breastfeeding (WHO / UNICEF 2002).
American Academy of Pediatrics: medication usually compatible with breastfeeding (AAP 2001).


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

Very Low Risk

Compatible. Not risky for breastfeeding or infant.

Low Risk

Moderately safe. Mild risk possible. Follow up recommended. Read the Comment.

High Risk

Poorly safe. Evaluate carefully. Use a safer alternative. Read the Comment.

Very High Risk

Not recommended. Cessation of breastfeeding or alternative.


  • Aciclovir
  • Aciklovir
  • Acycloguanosine
  • Asikloviiri
  • BW-248U


  • Ακυκλοβίρη (Greek)
  • أسيكلوفير (Arabic)
  • Ацикловир (Cyrillic)
  • 阿昔洛韦 (Chinese)
  • アシクロビル (Japanese)
  • C8H11N5O3 (Molecular formula)
  • 9-[(2-Hydroxyethoxy)methyl]guanine; 2-Amino-1,9-dihydro-9-(2-hydroxyethoxymethyl)-6H-purin-6-one (Chemical name)
  • D06BB03 (ATC Code/s)
  • J05AB01 (ATC Code/s)
  • S01AD03 (ATC Code/s)


  1. Butler DC, Heller MM, Murase JE. Safety of dermatologic medications in pregnancy and lactation: Part II. Lactation. J Am Acad Dermatol. 2014Abstract
  2. 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. 2012Abstract Full text (link to original source) Full text (in our servers)
  3. 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. 2002Abstract
  4. WHO / UNICEF. BREASTFEEDING AND MATERNAL MEDICATION Recommendations for Drugs in the Eleventh WHO Model List of Essential Drugs. Department of Child and Adolescent Health and Development (WHO/UNICEF) 2002 Full text (link to original source) Full text (in our servers)
  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. 2001Abstract
  6. AAP - American Academy of Pediatrics Committee on Drugs. Transfer of drugs and other chemicals into human milk. Pediatrics. 2001Abstract Full text (link to original source) Full text (in our servers)
  7. Bork K, Kaiser T, Benes P. Transfer of aciclovir from plasma to human breast milk. Arzneimittelforschung. 2000Abstract
  8. Bork K, Benes P. Concentration and kinetic studies of intravenous acyclovir in serum and breast milk of a patient with eczema herpeticum. J Am Acad Dermatol. 1995Abstract
  9. Taddio A, Klein J, Koren G. Acyclovir excretion in human breast milk. Ann Pharmacother. 1994Abstract
  10. Don PC, Kizner R. Excretion of acyclovir in human breast milk. J Am Acad Dermatol. 1991Abstract
  11. Meyer LJ, de Miranda P, Sheth N, Spruance S. Acyclovir in human breast milk. Am J Obstet Gynecol. 1988Abstract
  12. Lau RJ, Emery MG, Galinsky RE. Unexpected accumulation of acyclovir in breast milk with estimation of infant exposure. Obstet Gynecol. 1987Abstract