Can I take flucloxacillin while pregnant or breastfeeding?
A plain-words look at what the NHS, the US drug label and LactMed say about flucloxacillin.
In short
Pregnancy: Flucloxacillin can be taken while you're pregnant. Check with a doctor or pharmacist before you take it.
Breastfeeding: You can take flucloxacillin while breastfeeding.
Your doctor, midwife or pharmacist can help you decide.
What this means for you
Pregnancy
- Flucloxacillin can be taken while you're pregnant.
- Check with a doctor or pharmacist before you take it.
Breastfeeding
- Just tiny amounts of flucloxacillin reach breast milk, so it's unlikely to cause side effects in your baby.
- Always check with a doctor or pharmacist before you take it.
- Treating an infection while you're breastfeeding matters, because if it's not treated it could make you ill.
- Side effects in breastfed babies from medicines their mother takes are very rare.
- Even so, it's important to keep an eye on your baby while you take any medicine and breastfeed.
- Until you've had advice about your baby's symptoms, keep taking flucloxacillin and carry on breastfeeding as normal.
When to get help
- Contact a healthcare professional or call 111 (in the UK) as soon as you can if your baby is not feeding as well as they usually do; is vomiting or has diarrhoea; or has oral thrush (a fungal infection in the mouth) or a skin rash.
- If your baby has any other symptoms, or you're worried about them, you can still call 111 or get in touch with any healthcare professional.
Talk to your doctor or pharmacist
This page is educational, not advice for your own situation. Talk to your doctor, midwife or pharmacist before you start, stop or change any medicine in pregnancy or while breastfeeding.
The details: what each source says
Flucloxacillin in pregnancy
The NHS says
Flucloxacillin can be taken while you're pregnant. Check with a doctor or pharmacist before you take it.
In our words, from the NHS page Flucloxacillin (nhs.uk). Contains public sector information licensed under the Open Government Licence v3.0 (OGL v3.0). The NHS does not endorse this site.
Flucloxacillin while breastfeeding
The NHS says
You can take flucloxacillin while breastfeeding.
Just tiny amounts of flucloxacillin reach breast milk, so it's unlikely to cause side effects in your baby. Always check with a doctor or pharmacist before you take it.
Treating an infection while you're breastfeeding matters, because if it's not treated it could make you ill.
Side effects in breastfed babies from medicines their mother takes are very rare. Even so, it's important to keep an eye on your baby while you take any medicine and breastfeed.
Contact a healthcare professional or call 111 (in the UK) as soon as you can if your baby is not feeding as well as they usually do; is vomiting or has diarrhoea; or has oral thrush (a fungal infection in the mouth) or a skin rash.
If your baby has any other symptoms, or you're worried about them, you can still call 111 or get in touch with any healthcare professional.
Until you've had advice about your baby's symptoms, keep taking flucloxacillin and carry on breastfeeding as normal.
In our words, from the NHS page Flucloxacillin (nhs.uk). Contains public sector information licensed under the Open Government Licence v3.0 (OGL v3.0). The NHS does not endorse this site.
LactMed says
Floxacillin (flucloxacillin) is not approved for marketing in the United States by the U.S. Food and Drug Administration. It is acceptable to use during breastfeeding and is frequently used abroad to treat mastitis in nursing mothers.[1-3] Limited information indicates that floxacillin levels in milk are low and 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. Floxacillin is acceptable in nursing mothers.
“Summary of Use during Lactation”, LactMed record “Floxacillin” (LM1083), quoted verbatim. Everything LactMed reports about Floxacillin while breastfeeding.
Sources
- NHS, Flucloxacillin (nhs.uk), page last reviewed 26 June 2025. Paraphrased. Contains public sector information licensed under the Open Government Licence v3.0.
- Drugs and Lactation Database (LactMed), National Institute of Child Health and Human Development (NICHD), via NCBI Bookshelf, record “Floxacillin” (LM1083), bulk release of 22 September 2026. LactMed on NCBI Bookshelf. Public domain; quoted verbatim. LactMed is a registered trademark of the U.S. Department of Health and Human Services.
Sources checked 26 September 2026. How we source and check every page.
Educational summary of named sources, not medical advice.