All penicillin antibitotics can be used during breastfeeding with precautionary infant monitoring (1):
- flucloxacillin, phenoxymethylpenicillin (penicillin V) and the broad-spectrum penicillins, such as amoxicillin and ampicillin, are the preferred choices as there is more evidence and experience to support their use
- pharmacokinetic properties and characteristics of all the penicillins are very similar
- although protein binding and bioavailability vary between the different penicillins, they are all acidic in nature and therefore only negligible quantities pass into milk
- drugs cross membranes in an un-ionised form (2)
- milk is generally slightly more acidic (pH 7.2) than the mother’s plasma (pH 7.4) so it attracts weak organic bases such as oxycodone and codeine
- such drugs become ionised and ‘trapped’ in the milk
- conversely, weak organic acids such as penicillin tend to be ionised and held in maternal plasma
- 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 (3)
- has been the occasional case report of rash, nausea, irritability and drowsiness; these were usually mild and self-limiting, and could be attributable to other causes (1)
- treatment choice should be primarily based on clinical indications and in line with national and local antimicrobial policy, with suitability in breastfeeding as a secondary consideration (1)
- ideally treatment should be at the lowest therapeutic dose for shortest duration of time
Use of combination penicillin preparations during breastfeeding
- some penicillins are combined with beta-lactamase inhibitors such as clavulanic acid (co-amoxiclav) or tazobactam (combined with piperacillin as Tazocin®), which help to minimise the risk of antimicrobial resistance
- there is no information on how much passes into breastmilk - however, studies have not identified any concerns for their use in breastfeeding (1)
Breast milk levels
- is limited published evidence of use in breastfeeding (1)
- studies for amoxicillin, ampicillin, benzylpenicillin (penicillin G), flucloxacillin, phenoxymethylpenicillin (penicillin V) and piperacillin show negligible levels in breast milk
- is no published information for pivmecillinam or temocillin, however breast milk levels are expected to be low
Infant monitoring
- as a precaution, monitor for gastro-intestinal disturbances, oral candida infection, hypersensitivity reactions (including rashes or breathing problems), nausea, irritability, and drowsiness
- precautionary infant monitoring will quickly pick up any potential issues
- further investigation is usually required before any issues or side effects can be attributed to the medicine (1)
- is a theoretical risk of hypersensitivity in the infant after exposure to penicillins through breast milk (1)
- foetal exposure to antibiotics through the placenta may cause sensitisation
- further exposure may result in allergic reactions, even from the negligible quantities seen in breast milk
- therefore, as a precaution, the infant should be monitored for signs of hypersensitivity which includes rashes and breathing problem
Treatment of infant infections with penicillin based antibiotic if breastfeeding mother also on penicillin
- if the infant needs treatment themselves with a penicillin or other antibiotic, they should receive the appropriate infant therapeutic dose, regardless of concomitant exposure through breast milk (1)
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