Azithromycin, clarithromycin or erythromycin can be used with precautionary infant monitoring. Recommendations apply to full term, healthy infants.

General considerations

It is important to complete an individual risk assessment for your patient and to apply the principles of prescribing in breastfeeding when looking at the available information and making treatment decisions.


All macrolide antibiotics can be used during breastfeeding with precautionary infant monitoring.

Treatment choice, duration and dose should be primarily based on clinical indications and in line with national and local antimicrobial policy, with suitability in breastfeeding as a secondary consideration.

Reported side effects are not specific to a particular macrolide and are generally mild in nature.

Infant effects

The effect of the macrolide exposure on the infant needs to be considered.

Oral and gut microflora

Exposure to antimicrobials can affect the infant’s natural balance of microflora.

In rare cases, antibiotic exposure has disturbed this balance and caused gastrointestinal disturbances or candidiasis. These effects are generally mild and resolve upon treatment discontinuation.

Treatment of infant infections

There is no conclusive information on whether the concentrations the infant is exposed to through breast milk are enough to be bactericidal or cause bacterial resistance.

If the infant needs treatment themselves with a macrolide or other antibiotic, they should receive the appropriate infant therapeutic dose, regardless of concomitant exposure through breast milk.


There is a theoretical risk of hypersensitivity in the infant after exposure to macrolides through breast milk. 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.

As a precaution, the infant should be monitored for signs of hypersensitivity which includes rashes and breathing problems.

Hypertrophic pyloric stenosis

There is conflicting data regarding whether there is an increased risk of infantile hypertrophic pyloric stenosis from exposure to macrolides via breast milk.

Some studies have noted an increased risk during the first 90 days of life, and especially in the first 2 weeks after birth. However, other studies fail to confirm this association. This risk might be increased with erythromycin, although this may simply reflect greater use. In many studies the macrolide was not specified.

Specific recommendations

Patient Information

The NHS website provides advice for patients on the use of specific medicines in breastfeeding.

Contact us

Get in touch with the UK Drugs In Lactation Advisory Service (UKDILAS), our specialist breastfeeding medicines advice service if you need support in the following situations:

  • you need further advice
  • the medicine in question is not included here
  • the infant is unwell or premature
  • multiple medicines are being taken

About our recommendations

Recommendations are based on published evidence where available. However, evidence is generally very poor and limited, and can require professional interpretation. Assessments are often based on reviewing case reports which can be conflicting and lack detail.

If there is no published clinical evidence, assessments are based on: pharmacodynamic and pharmacokinetic principles, extrapolation from similar drugs, risk assessment of normal clinical use, expert advice, and unpublished data. Simulated data is now increasingly being used due to the ethical difficulties around gathering good quality evidence in this area.


Full referencing is available on request.

Update history

  1. Editorial change (removal of duplicated clinical considerations section)
  1. Published

Print this page