Can you take oxacillin 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.
Limited information indicates that oxacillin produces low levels in milk that are not expected to cause adverse effects in breastfed infants. Occasionally disruption of the infant's gastrointestinal flora, resulting in diarrhea or thrush have been reported with penicillins, but these effects have not been adequately evaluated. Oxacillin is acceptable in nursing mothers.
Quoted from Oxacillin — Drugs and Lactation Database (LactMed®), National Institute of Child Health and Human Development, revised November 15, 2024.
What LactMed would consider instead
LactMed ends this record by naming the drugs it would consider in place of oxacillin. Whether any of them fits depends on what you are treating — this is the database’s list, not a recommendation from us.
- Cefazolin
- Cephalexin
- Dicloxacillin
- Floxacillin
- Methicillin
- Nafcillin
- Doxycycline
- Linezolid
- Minocycline
- Trimethoprim-Sulfamethoxazole
- Vancomycin
How much oxacillin gets into breastmilk
Maternal Levels. After 3 to 4 doses of oxacillin 500 mg orally in 10 women, the highest level detected was 0.2 mg/L in two women 4 hours after the dose. In the other 8 women, milk levels were less than 0.2 mg/L at times between 1 and 3.75 hours after the dose.
One woman received oral oxacillin 3 grams daily. After the third dose, milk oxacillin levels ranged from 0.04 to 0.1 mg/L, with the peak occurring at 3 hours after the dose. The authors estimated that a breastfed infant would receive 0.3 mg daily of oxacillin in milk.
In 10 women with mastitis who received 1 gram of oxacillin orally 3 times daily for 5 to 6 days, the average milk concentrations ranged from 0.43 to 0.68 mg/L.
Repeated injections of oxacillin 1 gram intramuscularly every 6 hours for 6 to 9 days in 15 women with unilateral mastitis yielded oxacillin milk levels that reached a peak of 0.49 mg/L at 3 hours after the first dose on the first day in the healthy breast, and somewhat lower levels in the breast with mastitis. After the last dose, peak milk levels of 0.64 mg/L occurred 6 hours after the dose in the unaffected breast with slightly lower levels in the breast with mastitis.
After a single intramuscular dose of 500 mg of oxacillin in 2 women, milk levels ranged from 0.18 to 0.7 mg/L between 1 and 4 hours, with the peak occurring at 2 to 4 hours after the dose. Only a trace was detectable at 6 hours after the dose.
In 15 women given a single 1 gram dose of oxacillin intravenously, milk levels averaged 0.68 mg/L at 2 hours after the dose.
Infant Levels. Ten women with mastitis received 1 gram of oxacillin orally 3 times daily for 5 to 6 days. Oxacillin was detectable in the urine in 5 of 6 of the breastfed infants in whom it was measured. Urine concentrations ranged from 0.2 to 3.7 mg/L.
What has been seen in breastfed infants
Relevant published information was not found as of the revision date.
Effects on milk supply
Relevant published information was not found as of the revision date.
Frequently asked questions
Can you take oxacillin while breastfeeding?
Limited information indicates that oxacillin produces low levels in milk that are not expected to cause adverse effects in breastfed infants. The full record is quoted on this page, and the decision is one to make with the person who prescribed it — LactMed itself states it is not a substitute for professional judgement.
What can I take instead of oxacillin while breastfeeding?
LactMed lists Cefazolin, Cephalexin, Dicloxacillin, Floxacillin, Methicillin, Nafcillin, Doxycycline, Linezolid, Minocycline, Trimethoprim-Sulfamethoxazole, Vancomycin as alternate drugs to consider. That is the database's own list for this drug — whether any of them suits you depends on what you are treating.
Does oxacillin pass into breastmilk?
LactMed's measured drug levels for oxacillin are quoted in full on this page, under "How much gets into breastmilk".
Do I need to pump and dump after taking oxacillin?
LactMed does not frame its records that way — it reports measured drug levels in milk and what has been observed in breastfed infants, which is what this page quotes. "Pump and dump" advice for a specific drug and dose should come from your clinician or a pharmacist, not from a general rule.
More on oxacillin
LactMed states that the information it presents is not a substitute for professional judgement, and that you should consult your healthcare provider for breastfeeding advice related to your particular situation. Nothing on this page is medical advice.