Drugs excreted in breast milk

Check the summary of product characteristics and the latest edition of the British National Formulary before prescribing any drug.

Most drugs taken by the mother are excreted in small amounts in breast milk.

• it is extremely difficult to predict the effect of a maternal drug on the child as the active dose is dependent on several variables, e.g. total daily drug dose, rate of body clearance, plasma binding, volume of milk ingested, rate of absorption and distribution within child.

The following classification is used by the WHO on the drugs used during breastfeeding:

• avoid
  • e.g - anticancer drugs (antimetabolites), radioactive substances (until isotope clears)
  • breastfeeding is contra-indicated, if essential mother should stop breastfeeding until treatment is completed. If treatment is prolonged, she may need to stop breastfeeding altogether (1)
• avoid if possible, may inhibit lactation
  • e.g. - oestrogens, including estrogen-containing contraceptives, thiazide diuretics, ergometrine
  • if a mother has to take one of these drugs for a short period, she does not need to give artificial milk to her baby. She can offset the possible decrease in milk production by encouraging her baby to suckle more frequently.
• avoid if possible, monitor infant for side-effects
  • e.g. - selected psychiatric drugs and anticonvulsants
  • used when they are really essential for the mother’s treatment and when no safer alternative is available
  • give clear instructions about observing the baby and the importance of frequent follow-up
  • if side-effects occur, stop the drug. If it is not possible to stop the drug, stop breastfeeding and feed the baby artificially until treatment is completed
    
    
• antibiotics and breastfeeding:
  • penicillins and cephalosporins are drugs of choice in breastfeeding - if no maternal allergy to penicillins/cephalosporins A review has stated (3):
    • Safe for administration:
      • aminoglycosides
      • amoxicillin
      • amoxicillin-clavulanate
      • antitubercular drugs
      • cephalosporins
      • macrolides
      • trimethoprim-sulphamethoxazole
      • trimethoprim - the BNF states that '..short-term use not known to be harmful'
        
        
    • Effects not known/to be used with caution:
      • chloramphenicol
      • clindamycin
      • dapsone
      • mandelic acid
      • metronidazole (low dose)
      • nalidixic acid
      • nitrofurantoin - the BNF states '..avoid; only small amounts in milk but could be enough to produce haemolysis in G6PD-deficient infants..'
      • tetracyclines
        
    • Not recommended:
      • metronidazole (single high dose)
      • quinolones
• compatible with breastfeeding
  • safe in usual dosage
  • e.g.
    • analgesics and antipyretics: short courses of paracetamol, acetylsalicylic acid, ibuprofen;
    • antibiotics: ampicillin, amoxicillin, cloxacillin and other penicillins, erythromycin
    • bronchodilators (e.g. salbutamol), corticosteroids, antihistamines, antacids

Common sense precautions include

• advising the mother to take as few non-prescribed drugs as possible and careful consideration of each prescribed drug. As an approximate guide, the drugs that are safe to use during pregnancy are those which are safe to use during breast feeding.

General advice concerning the pharmacodynamics of less toxic drugs:

• choose preparations with shorter half-lives
• suggest feeds at the time of minimal plasma concentration e.g. just before the next drug dose
• choose routes of administration which are appropriate to the condition but minimise plasma concentration, e.g. topical steroids as opposed to oral where possible

Notes:

• chloramphenicol
  • systemic chloramphenicol is normally contra-indicated in breastfeeding mothers due to the theoretical risk of aplastic anaemia, and reported adverse effects in breastfeeding infants, although the quality of this evidence is poor
• topical chloramphenicol (2)
  • chloramphenicol eye and ear preparations can be used with caution during breastfeeding
    • however - should not be used in mothers where there is a past or family history of blood dyscrasias
    • fusidic acid or gentamicin preparations would be preferred, if clinically appropriate
  • milk levels
    • are no data available on the levels of chloramphenicol in breast milk after topical administration of chloramphenicol whilst breastfeeding
      • based on the drug properties, and minimal absorption, levels are predicted to be very low
  • risk of haematological toxicity
    • is conflicting evidence regarding whether topical chloramphenicol can cause aplastic anaemia
      • thus is still a theoretical risk that the very low amounts of chloramphenicol which may pass into the breast milk from topical formulations could cause aplastic anaemia
  • no side-effects have been reported in breastfed infants who have been exposed to topical chloramphenicol
  • advice re: monitoring the infant if breastfeeding mother using topical chloramphenicol
    • if the mother uses topical chloramphenicol, the infant should be monitored for the following side-effects as a precautionary measure:
      • abdominal distension
      • poor feeding
      • sedation
      • difficulty breathing
      • vomiting or diarrhoea
      • anaemia
      • rash
      • ashen grey skin colour
    • this will quickly pick up any potential issues
      • usually, further investigation is required before attributing any side-effects to the medicine
    • precautionary monitoring for signs of aplastic anaemia (anaemia, rash, bruising or bleeding) should also continue for a period of time after the course has finished
  • further information
    • is no published evidence available on using topical administered chloramphenicol while breastfeeding, including the levels that might pass into breast milk
    • however, based on the drug properties and minimal systemic absorption, milk levels are predicted to be very low and unlikely to cause infant side effects

Reference:

1. World Health Organization (WHO) 2002. Breastfeeding and maternal medication. Recommendation for drugs in the eleventh WHO model list of essential drugs
2. NHS Specialist Pharmacy Service (May 2026).Using chloramphenicol in breastfeeding
3. Mathew JL. Effect of maternal antibiotics on breast feeding infants Postgrad Med J 2004;80:196-200.