Can you take ganciclovir while breastfeeding?

What LactMed says

The National Library of Medicine’s own summary, quoted in full. We do not write a verdict of our own on this question, and we do not compress theirs into a label.

Several factors might affect the decision to use ganciclovir in a nursing mother. No information is available on the clinical use of ganciclovir during breastfeeding. Cytomegalovirus (CMV) can be transmitted to infants though breastmilk, with preterm and immunocompromised infants at greatest risk. No information is available on any changes in the risk of transmission if the mother is being treated with ganciclovir. Although the manufacturer recommends avoiding breastfeeding during ganciclovir use because of the risk of infant drug toxicity, neonates with CMV infections are often treated directly with ganciclovir.

It is unlikely that topical ophthalmic ganciclovir administration results in sufficient systemic absorption to produce detectable quantities in breastmilk. To substantially diminish the amount of drug that reaches the breastmilk after using eye drops, place pressure over the tear duct by the corner of the eye for 2 to 5 minutes, then remove the excess solution with an absorbent tissue.

Quoted from Ganciclovir — Drugs and Lactation Database (LactMed®), National Institute of Child Health and Human Development, revised February 15, 2026.