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FACTSHEET

Antibiotics and Breastfeeding

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This factsheet is intended to provide access to relevant evidence-based information. The national guidelines, research, data, pharmacokinetic properties and links shared are taken from various reference sources, they were checked at the time of publication for appropriateness and were in date. These are provided where we believe the information may be useful but we do not take any responsibility for their content. The factsheet is provided to empower users to make an informed decision about their treatment; but it does not constitute medical advice and cannot replace medical assessment, diagnosis, treatment or follow up from appropriately trained healthcare professionals with relevant competence.

The Breastfeeding Network factsheets will be reviewed on an ongoing basis, usually within three years or sooner where major clinical updates or evidence are published. No responsibility can be taken by the Breastfeeding Network or contributing authors for the way in which the information is used.

If you have any questions about this information, you can contact the Drugs in Breastmilk team through their Facebook page  or on druginformation@breastfeedingnetwork.org.uk.

You can usually continue to breastfeed whilst taking antibiotics.

Antibiotics are generally prescribed more sparingly than they were in the past in the light of increasing evidence of lack of benefit in self-limiting conditions and increased resistance in some organisms. Antibiotics are not appropriate in viral conditions such as the majority of coughs and colds. However, there are times when their use is important and even lifesaving. The use of antibiotics to treat mastitis is discussed in the BfN leaflet Breastfeeding and Mastitis.

Choice of antibiotic to treat any condition depends primarily on the organism likely to be causing the symptoms, taking into account any previous allergies e.g. rash in response to penicillin.

Most antibiotics can produce excessively loose motions in your baby, with the appearance of diarrhoea. Some infants appear more unsettled with tummy aches or colic. These effects are not clinically significant and do not require treatment. The value of continued breastfeeding outweighs the temporary inconvenience. In theory, exposure may sensitise your baby to later doses, e.g. penicillin allergy, but this is exceedingly rare. Large doses of antibiotics may encourage overgrowth of thrush (candida) in you by killing your natural gut bacteria. Some women find taking supplements of acidophilus or live yoghurt beneficial to redress the balance. Breastmilk contains all the necessary biological factors to heal your baby’s gut.

The following antibiotics are all safe to take whilst breastfeeding:

  • Amoxycillin, Amoxil®
  • Azithromycin, Zithromax®
  • Cefaclor, Distaclor®
  • Cefuroxime, Zinnat®
  • Cephalexin, Cefalexin, Keflex®
  • Cephradine, Velosef®
  • Clarithromycin, Klaricid®
  • Co-amoxiclav, Augmentin®
  • Co-fluampicil, Flucloxacillin + Ampicillin, Magnapen®
  • Erythromycin, Erymax®, Erythrope®, Erythrocin®
  • Flucloxacillin, Floxapen®,
  • Penicillin V, Phenoxymethyl penicillin  
  • Pivmecillinam, Selexid®
  • Trimethoprim, Monotrim®

All are available as liquid forms to treat infant infections.

Intra-venous antibiotics

Some antibiotics e.g. gentamycin, meropenem are given intra-venously as they poorly absorbed from the gut. Any drug passing into breastmilk is therefore unlikely to be absorbed in sufficient quantities by the baby and there is no need to cease breastfeeding on safety grounds. However, you may not feel well enough to breastfeed or may need your baby to be cared for by another adult and brought to you for feeding.

Tetracyclines

It was believed in the past that tetracycline antibiotics were contra-indicated in breastfeeding because they could stain the infant’s teeth (even if they had not appeared). In short courses (less than a month) this appears not to be a problem as the drug forms a complex with the calcium in the milk and is not absorbed by the baby. Long courses, e.g. for acne, should be avoided wherever possible.

The drugs in this family are:

  • Tetracycline
  • Oxytetracycline
  • Minocycline (Minicin®)
  • Doxycycline (Vibramycin®)
  • Lymecycline (Tetralysal®)

Metronidazole

Metronidazole (Flagyl®) has been said to impart an unpleasant taste to your milk and cause your baby to reject it. It has not been possible to trace the original research which suggested this or who tasted the milk and made this conclusion. Babies do not appear to be concerned by the frequent variation in the taste of breastmilk which occurs naturally. Occasionally it can alter the colour of the milk. In the US single doses of 2g are used and breastfeeding is temporarily interrupted. In the UK doses of 200-400milligrammes three times a day are used and breastfeeding can continue. Intra-venous use does not appear to pose any difficulties in lactation.

An oral dose 400milligrammes three times daily produced milk levels of 15.52 μg/ml and 200milligrammes three times a day an equivalent dose to the infant of 3milligrammes/kg/day compared to the dose of 22.5milligrammes/kg/day given therapeutically to children. Anecdotally, increased maternal consumption of garlic masks the taste of the Metronidazole.

Other antibiotics

  • Ciprofloxacin (Ciproxin®) can cause problems in the joints of juvenile animals exposed to it. The relevance to breastfeeding is unknown, and short maternal courses are unlikely to pose problems. Other antibiotics are preferable e.g. trimethoprim or nitrofurantoin as first line for simple urinary tract infection.
  • Nitrofurantoin (Furadantin®, Macrodantin®) – only small amounts are excreted into breastmilk but may cause haemolysis in G6PD deficient infants (a comparatively rare condition involving enzyme deficiency). It may colour your urine, tears and milk yellow. This is not significant.
  • Vancomycin and teicoplanin are used to treat multiple resistant staphylococcus aureus (MRSA). The side effects of these drugs are potentially severe and their use requires blood counts and kidney and liver function tests. Use to treat MRSA is generally given by intra-venous and intra-muscular absorption. The British National Formulary (BNF) states that oral absorption is poor but there is little information on use in lactation and studies of milk transfer.
  • Clindamycin is available as a tablet and vaginal gel. The tablets have rarely produced antibiotic-associated colitis in breastfed babies (one reported case) and babies exposed should be observed for blood in faeces. Vaginal application is unlikely to produce adverse effects in babies although 30% is absorbed into milk.
  • Co-trimoxazole (Septrin®, Bactrim®) is a combination of 2 drugs: trimethoprim and sulphamethoxazole. It is used less commonly than it was in the past because of unwanted adverse effects and that single antibiotics were deemed more effective and therefore preferable. The combination drug has very specific indications for adults and children and is not prescribed routinely. Co-trimoxazole should not be prescribed if you are breastfeeding in the first 6 weeks after birth, where there is a possibility of G6PD deficiency or if your baby is still jaundiced.  Both sulphamethoxazole and trimethoprim are secreted into breastmilk in low levels and in situations outside those mentioned above breastfeeding can continue as normal

Topical antibacterial agents

There is no evidence that topical anti-infective creams, ointments and gels are sufficiently absorbed to pass into breastmilk. If they are applied to the nipple any visible product should be gently wiped off prior to breastfeeding.

  • Fusidic Acid, (Fucidin®)
  • Mupirocin, (Bactroban®)

Bibliography

© The Breastfeeding Network. Last full update October 2022. Last amended April 2025.