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Linezolid Pregnancy and Breastfeeding Warnings

Medically reviewed by Last updated on Jun 14, 2021.

Linezolid is also known as: Zyvox

Linezolid Pregnancy Warnings

This drug should be used during pregnancy only if clearly needed and the benefit outweighs the risk to the fetus.

AU TGA pregnancy category: B3
US FDA pregnancy category: C

Animal studies have failed to reveal evidence of teratogenicity, but embryofetal toxicity was observed at maternotoxic doses. Embryofetal toxicity included increased postimplantation embryolethality (including total litter loss), decreased fetal weights, and increased rate of costal cartilage fusion in mice with maternal toxicity (clinical signs, reduced weight gain); decreased fetal weights, reduced sternebrae ossification, decreased pup survival, and mildly delayed maturation in rats with slight maternal toxicity (reduced weight gain); and reduced fetal weights in rabbits with maternal toxicity (clinical signs, reduced weight gain, reduced food intake). Placental transfer of this drug and/or its metabolites was observed in rats. There are no controlled data in human pregnancy.

AU TGA pregnancy category B3: Drugs which have been taken by only a limited number of pregnant women and women of childbearing age, without an increase in the frequency of malformation or other direct or indirect harmful effects on the human fetus having been observed. Studies in animals have shown evidence of an increased occurrence of fetal damage, the significance of which is considered uncertain in humans.

US FDA pregnancy category C: Animal reproduction studies have shown an adverse effect on the fetus and there are no adequate and well-controlled studies in humans, but potential benefits may warrant use of the drug in pregnant women despite potential risks.

See references

Linezolid Breastfeeding Warnings

Drug levels in breast milk are likely effective against staphylococcal strains found in mastitis. Based on limited data, the maximum dose an infant would receive via breast milk would be much less than the usual infant dose (maximum infant dose: 30 mg/kg/day).

Milk samples were collected at 10 time points over 24 hours from a 32-year-old lactating woman after a single 600 mg oral dose. The peak breast milk drug level (12.4 mg/L) was reached 2 hours after dosing. Milk levels decreased with a half-life of 6.5 hours and were detectable up to 24 hours after dosing. Based on this data, an exclusively breastfed infant would receive about 2 mg/kg/day (estimated maximum) from the maximum recommended maternal dose.

A woman was treated with 600 mg orally every 12 hours for methicillin-resistant Staphylococcus aureus mastitis. Milk was pumped from both breasts 8 times daily on the 1st and 14th day of therapy. Peak breast milk drug levels averaged 9.75 and 18.73 mg/L on day 1 and 14, respectively. According to author calculation, a fully breastfed infant would receive 7.85% and 15.61% of the weight-adjusted maternal dose on day 1 and 14, respectively. Based on the milk level on day 14, a fully breastfed infant would receive 1.84 mg/kg/day.

LactMed: Use of this drug is not a reason to discontinue breastfeeding if it is required by the mother; alternate therapy may be preferred, especially if the nursing infant is premature or younger than 1 month.
-According to some authorities, breastfeeding is not recommended during use of this drug and should be discontinued before starting therapy.
-According to other authorities, caution is recommended.

Excreted into human milk: Yes

-The effects in the nursing infant are unknown; according to some experts, the nursing infant should be monitored for possible effects on the gastrointestinal tract (e.g., diarrhea, vomiting, candidiasis [thrush, diaper rash]).

See references

References for pregnancy information

  1. "Product Information. Zyvox (linezolid)." Pharmacia and Upjohn (2001):
  2. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0
  3. Cerner Multum, Inc. "Australian Product Information." O 0

References for breastfeeding information

  1. "Product Information. Zyvox (linezolid)." Pharmacia and Upjohn (2001):
  2. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0
  3. Cerner Multum, Inc. "Australian Product Information." O 0
  4. United States National Library of Medicine "Toxnet. Toxicology Data Network." (2013):

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.