Fluorouracil

The Basics

What is Fluorouracil?

Used to treat actinic or solar keratoses (scaly or crusted lesions [skin areas] caused by years of too much exposure to sunlight).

Brand names for Fluorouracil

Efudex

How Fluorouracil is classified

Antimetabolites, Antineoplastic Agents, Antimetabolites, Antineoplastic, Immunosuppressive Agents

Fluorouracil During Pregnancy

Fluorouracil pregnancy category

Category N/ANote that the FDA has deprecated the use of pregnancy categories, so for some medications, this information isn’t available. We still think it’s useful to list historical info, however, given what a common proxy this has been in the past.

What we know about taking Fluorouracil while pregnant

Efudex is contraindicated in women who are or may become pregnant during therapy. If this drug is used during pregnancy, or if the patient becomes pregnant while using this drug, the patient should be apprised of the potential hazard to the fetus.

Taking Fluorouracil While Breastfeeding

What are recommendations for lactation if you're taking Fluorouracil?

Most sources consider breastfeeding to be contraindicated during maternal antineoplastic drug therapy. It might be possible to breastfeed safely during intermittent therapy with an appropriate period of breastfeeding abstinence, but the duration of abstinence is not clear. Limited information indicates that a maternal continuous intravenous fluorouracil infusion at a dose of 200 mg/square meter daily produces undetectable levels in milk. If fluorouracil use is undertaken, monitoring of the infant’s complete blood count and differential is advisable. Chemotherapy may adversely affect the normal microbiome and chemical makeup of breastmilk.[1] Women who receive chemotherapy during pregnancy are more likely to have difficulty nursing their infant. Topical fluorouracil applied away from the breast should pose negligible risk for the breastfed infant; however, it is important to ensure that the infant’s skin does not come into direct contact with the areas of skin that have been treated.

Maternal / infant drug levels

Most sources consider breastfeeding to be contraindicated during maternal antineoplastic drug therapy. It might be possible to breastfeed safely during intermittent therapy with an appropriate period of breastfeeding abstinence, but the duration of abstinence is not clear. Limited information indicates that a maternal continuous intravenous fluorouracil infusion at a dose of 200 mg/square meter daily produces undetectable levels in milk. If fluorouracil use is undertaken, monitoring of the infant’s complete blood count and differential is advisable. Chemotherapy may adversely affect the normal microbiome and chemical makeup of breastmilk.[1] Women who receive chemotherapy during pregnancy are more likely to have difficulty nursing their infant. Topical fluorouracil applied away from the breast should pose negligible risk for the breastfed infant; however, it is important to ensure that the infant’s skin does not come into direct contact with the areas of skin that have been treated.

Possible effects of Fluorouracil on milk supply

A telephone follow-up study was conducted on 74 women who received cancer chemotherapy at one center during the second or third trimester of pregnancy to determine if they were successful at breastfeeding postpartum. Only 34% of the women were able to exclusively breastfeed their infants, and 66% of the women reported experiencing breastfeeding difficulties. This was in comparison to a 91% breastfeeding success rate in 22 other mothers diagnosed during pregnancy, but not treated with chemotherapy. Other statistically significant correlations included: 1. mothers with breastfeeding difficulties had an average of 5.5 cycles of chemotherapy compared with 3.8 cycles among mothers who had no difficulties; and 2. mothers with breastfeeding difficulties received their first cycle of chemotherapy on average 3.4 weeks earlier in pregnancy. Of the 9 women who received a fluorouracil-containing regimen, 8 had breastfeeding difficulties.[3]

Possible alternatives to Fluorouracil

None listed