Very low levels of montelukast appear in breastmilk. Montelukast is approved for use in children as young as 6 months of age and has been used in neonates in dosages far greater than the amounts in breastmilk. Amounts ingested by the infant would not be expected to cause any adverse effects in breastfed infants. International guidelines consider that leukotriene receptor antagonists can be used during breastfeeding.[1,2]