How To Stop Acidic Poo In Breastfed Babies? (2 Common Reasons & Solutions!)

How To Stop Acidic Poo In Breastfed Babies - Babe in Dreamland

Acidic poop in babies usually leads to an ugly and particularly irritating nappy rash.

If it’s not handled quickly, the nappy rash may turn into bright red blisters, which would make a baby’s bottom extremely sore.

If you experienced this with your baby – you know exactly how bad it can be!

So, naturally, you need to stop the acidic poop to prevent further inflammation of your baby’s sensitive skin.

To do that, you need to get to the bottom of what causes the acidic poop in the first place.

Read on to find the 2 most common reasons your breastfed baby has an acidic poop and how to stop it effectively.

How To Stop Acidic Poo In Breastfed Babies?

To stop the acidic poo in your baby, you must identify why it started. Most likely, it is caused by lactose overdose that occurs when a baby is taking too much foremilk and not enough hindmilk. Because of this, the milk is not being adequately digested but runs through the intestines causing explosive, acidic poo. The second reason is that baby is sensitive to something a breastfeeding mom is eating. Possibly, it is cow’s protein intolerance, although other food can also cause stomach issues. The solution is for the mom to eliminate the foods from her diet one by one until the baby’s digestive system settles down.

What Is Acidic Poo in Breastfed Babies?

Let’s start by explaining what acidic poop looks like and how to distinguish it from the “normal stuff” that comes out of your baby’s bowels.

Poop from a breastfed baby falls within a wide range of normal.

It is usually loose and unformed, seedy, and of mustard consistency. The colour range may vary from yellow and green to brown.

What isn’t normal is white, red, or black. If that’s the case, you should call the doctor, as it may indicate gastrointestinal bleeding, liver problem, or nutrient malabsorption.

A normal breastfed baby poop doesn’t smell bad.

In fact, its scent is very mild, sweet, and similar to milk or popcorn 🙂

Acidic poop, on the other hand, will have a distinctive, sour, and foul smell.

Trust me, the moment you smell it, you’ll know it isn’t a normal poo!

What’s more, its colour and consistency will trigger a red alert too. Because it will be green, foamy, frothy runny, and often explosive. The poo is usually accompanied by smelly gas, causing tummy aches.

The worst is the horrible bleeding rash that pops up on your baby’s nappy area.

No matter how quickly you change the nappy, the baby’s skin will get red and inflamed where the poo was touching. Hence the reason to get the acidic poo under control with no delay.

So, first, you must identify the reason behind the acidic poo.

1. Foremilk & Hindmilk Imbalance

The first reason for acidic poo is your baby is taking too much foremilk and not enough hindmilk, causing lactose overdose.

Lactose overdose usually happens when your baby feeds very often but for a short time. Therefore, you have the impression that your baby is hungry all the time.

This means that the baby receives foremilk continuously (diluted milk stored in the milk duct near the nipple). And never gets to take the hindmilk (milk that is high in calories, rich in fat and is stored in milk-making cells deep inside the breast), only available at the end of the feed. In other words, your baby fills up her stomach with the “skinny milk” which is being digested quickly and gets hungry very quickly.

Feeding often but quickly also means that the breast never gets completely empty and may also fill up quickly, which leads to overproduction of milk.

Why is that a problem?

Because foremilk is high in lactose, which is broken down by the enzyme lactase. Now, when the digestive system is overwhelmed with lactose, the milk is not being digested but continues to pass through the intestines. As a result, it begins to ferment in the lower bowel, causing the production of excessive gas and frothy and acidic poop or diarrhoea.


You need to ensure the breast is completely empty before offering the baby a second breast.

In that way, your baby will get fatty hindmilk.

So, all you need to do is to slightly tweak your feeding pattern. Voila.

And you can do this by introducing “block feeding“.

Block feeding means that you continue to nurse your baby from the same breast for two or more consecutive feeding within 6 hours window. After these 6 hours, you switch the sides and continue to feed on it for the next 6 hours.

Should your breast that is not being nursed become uncomfortable or engorged during the block feeding, express some milk to relieve the pressure. The last thing you want is to develop mastitis due to blocked milk ducts…

You should continue with block feeding until the baby’s poo gets back to normal and your supply settles down.

Block Feeding

Now, if oversupply is not your problem, nor do you suspect a lactose overdose – your baby may have a milk protein allergy or be allergic to another food.

2. Mom’s diet

The second possible reason for an acidic poo in your baby is sensitive to something you have eaten, and it is passed on to your breastmilk.

The most typical allergen is dairy products, specifically cow’s milk protein. Soya, caffeine, gluten, nuts, eggs, and fish are also widely known for causing digestive issues in babies.


It would be best if you started by eliminating dairy from your diet. Diary is always the first option because cows’ milk allergy is the most common childhood food allergy.

Note that it may take up to 3 weeks for your body to clear from the cow’s protein. If there is no improvement after this time, eliminate the next product on the list. After that, you must wait another few weeks to determine if your baby’s poo gets back to normal.

What is worth remembering is that even if your milk may cause your baby this discomfort, it is still the best food for your baby. So don’t think about changing to a formula!

Also, you may want to think about infant probiotics to boost your baby’s microbiome and help with digestion. Just remember to consult your baby’s doctor on the most appropriate supplement for your baby.

***As a side note, lactose intolerance is not the same as cow’s milk protein intolerance. Lactose intolerance in infants is a rare genetic disorder. The main symptom is failure to thrive from birth as a result of dehydration and difficulty absorbing nutrients from milk.

On the other hand, lactose intolerance in adults is a common digestive problem. It is caused by the fact that lactase production decreases as we age. Therefore, the ability to break down lactose is reduced and hence digestive issues.

Final Few Lines

Baby’s poop will tell you a lot about their health. So, it is worth paying close attention to your baby’s diaper during their first month of life.

If your little one has acidic poop, you should act fast to contain it. Because it may lead to a painful, blistery nappy rash that will take time and lots of effort to heal.

The acidic poop can be caused by these 2 common reasons:

  • Hind-milk overdose. In which case, you should adjust your breastfeeding routine to make sure your baby takes fatty milk as well.
  • Cow’s milk protein intolerance and another potential allergen. In such a case, it is imperative that you eliminate the food from your diet while continuing to breastfeed.
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