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Lactose overload

Lactose overload


How is lactose overload different to lactose intolerance?

Lactose overload is commonly seen in babies who are consuming large volumes of breastmilk from mothers who have an oversupply.

When does lactose overload happen?

Lactose overload  typically presents after mature milk has established (>4-6 weeks post birth) but less than 3 months of age. 

What’s the difference between lactose overload and lactose intolerane?

The difference between lactose overload and lactose intolerance is directly related to the amount of lactose in the baby’s diet and their digestive response.

Babies who suffer from intolerance are unable to process and digest NORMAL amounts of lactose. They will become irritable and have gastric upsets leading to weight LOSS.

Lactose overload babies struggle with EXCESSIVE amounts of lactose in their diet. While also irritable with gastric upsets, baby will still be well and GAINING weight.

How can oversupply cause lactose overload?

In cases of breastmilk oversupply, large volume/ low-fat content feeds progress through a baby’s gastrointestinal tract quickly, leaving lactose undigested. This lactose retains additional water and ferments in the lower bowel which produces gas.  As baby continues to be unsettled from lactose overload, he will appear hungry/distressed and therefore, (logically) be fed again.  However, frequent short feeds from alternating sides often continues the pattern of foremilk/hindmilk imbalance leading to further lactose overload.

What are some ways to prevent lactose overload?

Ensure the breast is empty before switching to the other breast (or feed from same breast twice before offering other side).  The aim of emptying one breast first is to facilitate hindmilk transfer (higher fat content breastmilk) This is because fat slows down GI processing, leading to increased lactose absorption.

Consider trying block feeding to prevent lactose overload – feeding the same breast for 3–4-hour block, before switching to the other breast for the next 3–4-hour block. Particularly helpful in cases of oversupply (when method used safely and correctly!) See our post about block feeding!

Written by Keryn Thompson, RM & IBCLC (L-301766)


Acker, M., 2011. Lactose Intolerance. Breastfeeding in America, 64(7-8), pp.592-594.

Bearzatto, A. and Amir, L., 2016. Overcoming challenges faced by breastfeeding mothers. 8th ed. The Royal Australian College of General Practitioners, p.45.

Douglas, P., 2013. Diagnosing gastro-oesophageal reflux disease or lactose intolerance in babies who cry alot in the first few months overlooks feeding problems. Journal of Paediatrics and Child Health, 49(4), pp.E252-E256.

Hiscock, H. and Douglas, P., 2010. The unsettled baby: crying out for an integrated, multidisciplinary primary care approach. 9th ed. Medical Journal of Australia, pp.533-536.

Lira, C., Tuel, S., Goldberg, L., Powers, N. and Parham, D., 2013. Diagnosing lactose intolerance: How PAs can facilitate breastfeeding: PAs who know how to test for diagnoses with symptoms similar to lactose intolerance may assist some mothers of colicky babies to continue breastfeeding. Journal of the American Academy of Physician Assistants, 26(4), pp.21-23.

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