medications, pregnancy complications, breastfeeding, pregnancy safety

Generic Name: Acyclovir
Indications: Herpes simplex or Varicella-Zoster infections.
FDA Drug Category: B

Acyclovir is a medication prescribed for herpes simplex infections of the mouth (cold sores), genital herpes, chickenpox, and shingles. Doctors can also prescribe acyclovir for pain associated with these conditions. The brand name for acyclovir is Zovirax.

General Precautions

While there are no known birth defects associated with the medication, it is not safe to take more than prescribed at any time, so pregnant women taking acyclovir should take the medication as outlined by your doctor.

If the drug is used for the treatment of a skin infection near or on the areola or nipple, the area should be cleaned before breastfeeding.

You don't have to stop taking the drug if you find out are pregnant during the course of treatment, but contact the prescribing doctor as soon as they find out you are pregnant.

Trying To Conceive (TTC)

There is no known effect on fertility when taking acyclovir, though you should let your OB or midwife know if you are taking this medicine.


Acyclovir is not thought to cause birth defects or pregnancy complications. The drug, whether taken orally or applied to the skin, does pass on to the fetus, but not in dangerous levels. Studies on possible birth defects associated with the first-trimester use of acyclovir revealed no side effects. The largest study included more than 1,500 infants.

If acyclovir is prescribed for a primary genital herpes infection (the first infection of the virus), it is extremely important that the course of treatment be completed as prescribed and all follow-up visits with the prescribing physician are followed.

There is limited information on the effects of acyclovir used in the second and third trimesters. The majority of pregnancy studies were completed on women using the medication during the first trimester.

Safe During Breastfeeding

There are no side effects associated with taking acyclovir while breastfeeding. Women who apply a topical form of the drug to the skin on the breast should wash the area well before breastfeeding.

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