Zovirax: Is Shingles Medication Safe while Nursing?

I was just diagnosed with herpes zoster -- shingles. I am nursing my  nine month old an average of four times a day, generally four to six hours between feedings. My doctor advised me to stop nursing, because he prescribed Zovirax 800 (acyclovir) and Percocet. After prompting him to do some checking he found that only a small amount of Acyclovir would be present in my breast milk but said Percocet could cause drowsiness in my baby. Are these medications really safe?


Debbi Donovan

Debbi Donovan is a Board Certified Lactation Consultant, as well as a retired La Leche League Leader. For more than a decade, Debbi... Read more

Acyclovir is an antiviral that is often used in the treatment of the herpes virus, chickenpox and shingles. It's approved by the American Academy of Pediatrics for use in nursing mothers.

Acyclovir does not cure herpes, but will often help the sores to heal more quickly, and will also help to relieve the associated pain.

The average adult half-life of Acyclovir is 2.4 hours. This means that in 4.8 hours., approximately 75 percent of this medication will have cleared from your system. It peaks in your bloodstream approximately one and a half to two hours after administration. The peak of a medication in your bloodstream generally corresponds to peak levels in your milk. A general rule is to avoid nursing at the time a drug peaks in your system.

Percocet is an oxycodone and acetaminophen combination and is used for pain relief. When these meds are used in combination they may provide better pain relief, at lower dosage, than either one on its own.

After a maternal dose of 5 to 10 mg. of oxycodone every four to seven hours, human milk levels have been reported to range from 5 to 226 micrograms per liter. At the highest concentration, this means that a baby taking in 1 liter (33 oz.) of human milk in a day would receive less than 2 percent of his mother's dose.

Oxycodone has an adult half-life of between three and six hours. It peaks in your bloodstream around one to two hours after administration.

When starting the Percocet for pain relief, you might want to try using the lowest recommended dose to see if you obtain the necessary relief from pain. You may also find you get enough pain relief from an over-the-counter analgesic, such as acetaminophen or ibuprofen, along with the acyclovir. Be sure to check first with your doctor.

Knowledge of a drug's half-life can be helpful in deciding the best times to dose, in relation to breastfeeding. In general, the best time to take a medication is immediately following nursing. In this way, particularly with a med that has a short half-life, there is a good chance much of the drug will have already cleared your system by the next feed.

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