All drugs transfer into milk. The extent is less than drug transfer during pregnancy.


General Advice

  • Consider non-drug measures first; avoid all drug therapy if possible, as the infant does not usually benefit from drug exposure via breast milk.
  • The infant risk depends on the dose ingested via milk, the oral availability, and the clearance in the infant.
  • Monitor the infant for adverse effects of the drug (e.g. failure to thrive, sedation, diarrhoea).
  • Dose after a feed where possible, to minimise drug exposure. Concentrations in the milk follow concentrations in maternal plasma.
  • Drug therapy rarely constitutes a reason to avoid breastfeeding. Consult readily with specialists in the area (e.g. Medicines Information).


Table 1: Drugs considered ‘Safe’ 1 when Breastfeeding Full-term Healthy Babies 2
1.            An infant dose <10% of the maternal dose on a mg/kg basis – Weight Adjusted Maternal Dose (WAMD) for drugs that do not have a low therapeutic index.

2.            This table is a guide only and the list is not exhaustive. Consult when the infant is premature, has significant renal or hepatic disease or G6PD deficiency, or when the maternal dose is unusually high or poorly controlled (e.g. social drugs).

Class Examples of Individual Drugs
Analgesics opioid analgesics* (short courses – < 2 days): morphine, oxycodone, codeine, paracetamol
Anticoagulants enoxaparin, heparin, warfarin (monitor infant INR)
Anticonvulsants* carbamazepine, phenytoin, valproate sodium
Antidepressants* SSRIs: citalopram, escitalopram, paroxetine, sertraline

SNRIs: venlafaxine

tricyclics: amitriptyline, nortriptyline

Antidiabetic insulin, metformin
Antihistamines cetirizine, loratadine
Antihypertensives ACE inhibitors: enalapril, quinapril

beta blockers: labetalol, metoprolol, propanolol

calcium channel blockers: diltiazem, nifedipine


Antimicrobials betalactams: amoxicillin, flucloxacillin

cephalosporins: cefalexin, ceftriaxone, cefazolin, cefuroxime, cefotaxime, cefepime, ceftazidime

macrolides: azithromycin, clarithromycin, erythromycin, roxithromycin

metronidazole (shorter courses – e.g. 400 to 600 mg BD for 7 to 10 days; avoid higher doses e.g. 2000 mg)


trimethoprim, trimethoprim/sulfamethoxazole

Antipsychotics* haloperidol, olanzapine, quetiapine, risperidone
Antivirals aciclovir, valaciclovir
Benzodiazepines* Short courses ( < 2 days) of midazolam, temazepam, zopiclone
Cardiac digoxin
Contraceptives progestogen-only, combined oral contraceptives after 6 weeks post-partum
Corticosteroids (short courses) prednisone (<20 mg/day)
Gastrointestinal drugs domperidone

proton pump inhibitors: omeprazole, pantoprazole



NSAIDs diclofenac, ibuprofen


* For all, monitor infant for adverse effects (e.g. sedation, jitteriness, lethargy, poor feeding).

Table 2: Drugs Considered ‘Unsafe’ During Breastfeeding

Consult Medicines Information ( 80900). May require individual decisions.

antineoplastic drugs
immunosuppressants (some)
iodine-containing agents
lithium (requires infant drug concentration monitoring)
retinoids (e.g. isotretinoin)
social drugs (e.g. alcohol, cannabis), opioids (long courses > 2 days)