Lactose overload in babies

Some babies take large amounts of breastmilk and have a lot of green, frothy poos. They may also be windy and crying or hard to settle after feeds.

Your baby may have more wet nappies and poos than normal in 24 hours. The poos may be green and frothy or explosive.    

Lactose overload can cause wind, pain and large runny poos. Your baby may also have nappy rash as the poo is more acidic. 
You may find your baby:

• is very unsettled
• has adequate to large weight gains
• has lots of wet nappies and many poos each day
• has green, frothy or explosive poo. Green poo on its own can be normal. If it is dark green but in small amounts, it can be a sign of too little milk.  

The roles of lactose and fat in breastmilk are important in understanding lactose overload. 

Lactose is a major part of breastmilk. The level of lactose stays about the same throughout a feed. The levels of fat increase within a feed as the amount of milk in your breast decreases. In the past, 'foremilk' and 'hindmilk' were terms used to describe breastmilk with lower or higher fat content. We now know that the change in fat content is very gradual.

Fat content in breastmilk is important for digestion. Fat slows down the movement of the milk through your baby’s gut, giving more time for the lactose to be broken down. If all the lactose isn’t digested properly your baby will experience wind and pain.

If you have a lot of milk your baby might finish feeding before getting enough of the fat rich milk. The same thing can happen if you switch breasts too soon.  

Your baby may have tummy pain and want to suck often for comfort. Giving more feeds and switching sides often can make the situation worse. Sometimes mums initially think they may have low milk supply because their baby always seems to be hungry.  

First take steps to reduce your oversupply. 

If after doing these for several weeks, you may want to try block feeding. 

Block feeding 

Only use this method for a few days if you are certain that you have too much milk and your baby is gaining weight well. An ABA breastfeeding counsellor or a lactation consultant can guide you through this process.

The aim of block feeding is to leave each breast full for longer. This reduces the speed that the breast makes milk. It also lets your baby have some feeds with higher fat content.

To block feed start with a 4-hour time period. Every time your baby wants to feed during this period, use the same breast. Then use the other breast for the next 4 hours, etc. Each time your baby returns to the same breast, they get a lower-volume, higher-fat feed that helps slow the milk moving through their gut.

If you find your breasts are too full and uncomfortable, reduce the time of each block.

In most cases you should see a difference in 1 to 3 days.  As soon as your baby's symptoms are relieved, stop block feeding.

Block feeding is designed to reduce your milk supply. Be careful not to keep using this method longer than you need to.  

© Australian Breastfeeding Association June 2025