How Long Does Dairy Take to Get Out of Your Breast Milk?

My baby has a severe dairy allergy. How long until dairy is out of my system so I can confidently nurse?
—Maggie

For a little background: If a child has a food allergy, they can react badly to breast milk if mom has eaten the allergenic food. This is because proteins in the food (in your case, milk proteins) pass into breast milk. A core symptom of this kind of allergy in a breastfed baby is bloody stools. The infant is often well-appearing and may gain weight fine, although allergies of this type are sometimes blamed for mood changes and general fussiness.

Estimates suggest that more than half of these allergies that appear in breastfed babies are a result of dairy, with eggs, corn, and soy also playing notable roles. The standard treatment protocol suggested by the Academy of Breastfeeding Medicine is an elimination diet: eliminate the offending food from the maternal diet, and see if the symptoms improve. Since the mechanism is exposure to the proteins in food, if you eliminate them, the problem will go away.

General advice: Symptoms should improve within 72 to 96 hours of stopping dairy, although moms are advised to continue the protocol for two to four weeks to fully evaluate. In your case, since it sounds like you know there is a dairy allergy, it’s worth asking your doctor whether there is a way to more precisely tell if you are still producing milk proteins.

A final note: Dairy elimination really does mean all dairy — all milk, ice cream, cheese, etc. If this doesn’t work, formula (soy-based) is a great option to consider.