Montelukast is a commonly used drug in allergies, and as you know, eveyone has allergies. This data shows that levels in milk are really quite low (RID = 0.68) and there is no obvious risk to a breastfeeding infant. TWH
Title: Transfer of Montelukast into Human Milk During Lactation.
Authors: Datta P, Rewers-Felkins K, Baker T, Hale TW.