Skip to Content

Acyclovir Pregnancy and Breastfeeding Warnings

Acyclovir is also known as: Sitavig, Zovirax

Acyclovir Pregnancy Warnings

Studies to determine the pharmacokinetics and tolerability of acyclovir given near term have reported maternal-cord ratios of 0.6 to 1.9 at delivery. The pharmacokinetics of acyclovir are not significantly affected by pregnancy. No toxicity has been reported in mother or neonates. The Acyclovir in Pregnancy Registry was established in 1984 by the manufacturer and the Centers for Disease Control and Prevention (CDC) and completed in April 1999. The incidence of adverse events reported, in the 749 pregnancies followed in women exposed to systemic acyclovir during the first trimester of pregnancy resulting in 756 outcomes, approximates that of the general population. Given the small size of the registry there are no sufficient data to assess the safety of acyclovir in pregnant women and the fetus. Women exposed to systemic acyclovir during pregnancy may contact the Registry by calling GlaxoSmithKline, Inc., at (888) 825-5249. In the U.S. Michigan Medicaid study involving surveillance of 229,101 pregnancies from 1985 to 1992, there were 478 first trimester exposures to systemic acyclovir. Eighteen major birth defects were reported (versus 20 expected), including cardiovascular defects, polydactyly, limb reduction, and hypospadia. There was no evidence of an association between first trimester use of acyclovir and major groups of malformations. Acyclovir use has also been studied in five patients prior to delivery to determine the effects on asymptomatic shedding of the virus and vertical transmission to the neonate. Asymptomatic shedding and viral transmission to the infant occurred in one case. The CDC recommend the use of intravenous acyclovir in pregnant patients for the treatment of life-threatening herpes infections, including encephalitis, pneumonitis and hepatitis. Acyclovir has also been recommended for the treatment of severe or progressive maternal varicella infection. However, the use of acyclovir during pregnancy for non-life-threatening infections or for suppressive therapy is not recommended by the CDC. Primary herpes simplex infection during pregnancy has been treated with acyclovir, although this practice remains controversial. Some have suggested that acyclovir decreases the incidence of adverse pregnancy outcomes such as prematurity and growth retardation.

Acyclovir has been assigned to pregnancy category B by the FDA. Nonstandard animal studies have produced fetal abnormalities, while standard animal testing failed to reveal evidence of teratogenicity. There are no controlled data in human pregnancy. Acyclovir is only recommended for use during pregnancy when benefit outweighs risk.

See references

Acyclovir Breastfeeding Warnings

In one woman, measurement of breast milk levels revealed her infant was exposed to 1% of the maternal dosage, or 0.73 mg/kg/day. No adverse effects were noted in this breast-feeding infant.

Acyclovir is excreted into and concentrated in human milk. Adverse effects in breast-feeding infants associated with exposure to acyclovir via breast milk have not been reported in the literature. Acyclovir is considered compatible with breast-feeding by the American Academy of Pediatrics. Moreover, acyclovir is used to treat viral infections in neonates.

See references

References for pregnancy information

  1. Randolph AG, Hartshorn RM, Washington AE "Acyclovir prophylaxis in late pregnancy to prevent neonatal herpes: a cost-effectiveness analysis." Obstet Gynecol 88 (1996): 603-10
  2. Brown ZA, Baker DA "Acyclovir therapy during pregnancy." Obstet Gynecol 73 (1989): 526-31
  3. U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control "1993 Sexually Transmitted Diseases Treatment Guidelines." MMWR Morb Mortal Wkly Rep 42 (1993): 27-46
  4. Frieden FJ, Ordorica SA, Goodgold AL, Hoskins IA, Silverman F, Young BK "Successful pregnancy with isolated herpes simlex virus encephalitis:case report and review of the literature." Obstet Gynecol 75 (1990): 511-3
  5. "Product Information. Zovirax (acyclovir)." Glaxo Wellcome, Research Triangle Park, NC.
  6. Stiffman MN, Adam P "Acyclovir in pregnancy for primary prevention of neonatal herpes." J Fam Pract 44 (1997): 29-30
  7. Gilbert GL "Chickenpox during pregnancy.." BMJ 306 (1993): 1079-80
  8. Briggs GG, Freeman RK, Yaffe SJ.. "Drugs in Pregnancy and Lactation. 7th ed." Philadelphia, PA: Lippincott Williams & Wilkins (2005):
  9. Johnson LG, Saldana LR "Herpes simplex virus hepatitis in pregnancy - a case report." J Reprod Med 39 (1994): 544-6
  10. Fletcher CV "The placental transport and use of acyclovir in pregnancy." J Lab Clin Med 120 (1992): 821-2
  11. Smego RA Jr, Asperilla MO "Use of acyclovir for varicella pneumonia during pregnancy." Obstet Gynecol 78 (1991): 1112-6
  12. CDC "Pregnancy outcomes following systemic prenatal acyclovir exposure--June 1, 1984-June 30, 1993." MMWR Morb Mortal Wkly Rep 42 (1993): 806-9
  13. Brown ZA, Watts DH "Antiviral theapy in pregnancy." Clin Obstet Gynecol 33 (1990): 276-89
  14. Henderson GI, Hu ZQ, Johnson RF, Perez AB, Yang Y, Schenker S "Acyclovir transport by the human placenta." J Lab Clin Med 120 (1992): 885-92
  15. Glorioso DV, Molloy PJ, Van Thiel DH, Kania RJ "Successful empiric treatment of HSV hepatitis in pregnancy. Case report and review of the literature." Dig Dis Sci 41 (1996): 1273-5
  16. Scott LL, Sanchez PJ, Jackson GL, Zeray F, Wendel GD "Acyclovir suppression to prevent cesarean delivery after first-episode genital herpes." Obstet Gynecol 87 (1996): 69-73
  17. Whitty JE, Renfroe YR, Bottoms SF, Isada NB, Iverson R, Cotton DB "Varicella pneumonia in pregnancy: clinical experience." Am J Obstet Gynecol 168 (1993): 427
  18. Hankey GJ, Bucens MR, Chambers JS "Herpes simplex encephalitis in third trimester of pregnancy: successful outcome for mother and child." Neurology 37 (1987): 1534-7
  19. Frenkel LM, Brown ZA, Bryson YJ, et al "Pharmacokinetics of acyclovir in the term human pregnancy and neonate." Am J Obstet Gynecol 164 (1991): 569-76
  20. Greenspoon JS, Wilcox JG, Mchutchison LB, Rosen DJD "Acyclovir for disseminated herpes simplex virus in pregnancy: a case report." J Reprod Med 39 (1994): 311-7
  21. Andrews EB, Yankaskas BC, Cordero JF, Schoeffler K, Hampp S, and The Acyclovir In Pregnancy Registry Advisory Comittee. "Acyclovir in pregnancy registry: six years' experience." Obstet Gynecol 79 (1992): 7-13
  22. Haddad J, Langer B, Astruc D, Messer J, Lokiec F "Oral acyclovir and recurrent genital herpes during late pregnancy." Obstet Gynecol 82 (1993): 102-4
  23. Blanchier H, Huraux JM, Hurauxrendu C, Lebaleur AS "Genital herpes and pregnancy - preventive measures." Eur J Obstet Gynecol Reprod Biol 53 (1994): 33-8

References for breastfeeding information

  1. Lau RJ, Emery MG, Galinsky RE "Unexpected accumulation of acyclovir in breast milk with estimation of infant exposure." Obstet Gynecol 69 (1987): 468-71
  2. 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 32 (1995): 1053-5
  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 186 (2002): 100-102
  4. Committee on Drugs, 1992 to 1993 "The transfer of drugs and other chemicals into human milk." Pediatrics 93 (1994): 137-50
  5. Taddio A, Klein J, Koren G "Acyclovir excretion in human breast milk." Ann Pharmacother 28 (1994): 585-7
  6. Roberts RJ, Blumer JL, Gorman RL, et al "American Academy of Pediatrics Committee on Drugs: Transfer of drugs and other chemicals into human milk." Pediatrics 84 (1989): 924-36
  7. Meyer LJ, de Miranda P, Sheth N, Spruance S "Acyclovir in human breast milk." Am J Obstet Gynecol 158 (1988): 586-8

See Also...

Disclaimer: Every effort has been made to ensure that the information provided by Cerner Multum, Wolters Kluwer Health and is accurate, up-to-date and complete, but no guarantee is made to that effect. In addition, the drug information contained herein may be time sensitive and should not be utilized as a reference resource beyond the date hereof. This material does not endorse drugs, diagnose patients, or recommend therapy. This drug information is a reference resource designed as supplement to, and not a substitute for, the expertise, skill , knowledge, and judgement of healthcare practitioners in patient care. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate that the drug or combination is safe, effective, or appropriate for any given patient. Multum Information Services, Inc. does not assume any responsibility for any aspect of healthcare administered with the aid of information Multum provides. Copyright 2000-2008 Multum Information Services, Inc. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the drugs you are taking, check with your doctor, nurse, or pharmacist.