Lactose Intolerance Vs Milk Allergy In Babies: Why Your Child Is Reacting To Milk

Lactose intolerance causes stomach aches and diarrhea, whereas milk allergy in babies can cause rashes and breathing trouble too.

Milk and babies usually go together – after all, it is the universal baby food. But if your baby shows symptoms like tummy pain, gas, or even a rash after having milk, you might be wondering what’s going on. The first step is to know that two different conditions – with two different triggers – may be to blame if your child is reacting badly to milk. Here’s everything you need to know about milk allergy and lactose intolerance, so you can zero in on what exactly is bothering your baby.

Lactose Intolerance Is The Inability To Digest A Milk Sugar

Lactose intolerance is a condition where the body finds it difficult to digest a sugar known as lactose which is present in milk (including breastmilk) and dairy products. An enzyme known as lactase which is produced in the small intestine is responsible for breaking down lactose. Here are a few things that you need to know about lactose intolerance in babies:

  • Lactose intolerance is very rare in full-term babies and typically starts to develop only after age 3.
  • Some babies are born with a genetic condition known as congenital lactase deficiency or congenital alactasia where they are unable to digest lactose from breastmilk. This can cause serious diarrhea and dehydration. Babies who suffer from this condition need to be fed with infant formula that is lactose-free. But congenital alactasia is a very rare condition. Incidentally, it is most commonly seen in Finland, where it occurs in 1 out of 60,000 babies.
  • In babies who are born prematurely, the small intestine may not produce sufficient lactase for a brief period after birth. But this typically improves on its own with time.1
  • Since lactase is produced in the small intestine, damage to the gut such as may be caused by a stomach bug can decrease the production of this enzyme and temporarily cause lactose intolerance. But this tends to get better in a few weeks or even days as the gut heals.2 3

Milk Allergy Is The Inability To Digest Milk Proteins

Cow’s milk allergy is a condition where your baby’s immune system reacts to proteins present in cow’s milk, resulting in an allergic reaction. Here are a few things that you need to know about cow’s milk allergy:

[pullquote]If your baby develops allergic symptoms after breastfeeding, hidden allergens passed on through breastmilk may be responsible. One study identified allergens such as cow’s milk, egg white, and peanuts and found that eliminating the allergen from the mother’s diet resulted in a symptom-free baby.4[/pullquote]

  • Cows’ milk allergy affects around 2% to 7.5% babies under the age of 1 and is a very common food allergy.
  • This condition usually develops when you introduce cow’s milk into the baby’s diet as a food or through formula. Though uncommon, it can also be seen in babies who have only breastmilk because cow’s milk consumed by the mother can be passed on through breastmilk. Breastmilk does not, however, directly cause an allergic reaction in babies – any allergic signs are usually traced to dairy the mother has had.
  • Cow’s milk allergy can manifest immediately, where you see symptoms of an allergic reaction within minutes of consuming milk. In some cases, there may be a delayed reaction, hours or even days after milk is consumed.5

Lactose Intolerance Causes Tummy Problems

[pullquote]Unlike a milk allergy, lactose intolerance does not cause breathing problems, hives, or eczema. And while lactose intolerance can cause quite a bit of abdominal discomfort, a serious allergic reaction to milk can potentially be life-threatening.6[/pullquote]

Lactose intolerance symptoms will vary from mild to severe depending on the amount of lactose that’s been consumed and that can be tolerated by the child. Symptoms to watch out for include:

  • Diarrhea
  • Vomiting
  • Abdominal pain and a rumbling sound in the stomach
  • Gas and bloating7

Cow’s Milk Allergy Can Cause Rashes And Breathing And Tummy Trouble

Cow’s milk allergy can cause symptoms like:

  • An itchy red rash or swelling in the face, lips, or around your eyes
  • Stomach problems like vomiting, constipation, diarrhea, colic, or stomach ache
  • A blocked or runny nose
  • Eczema which doesn’t get better with treatment

Sometimes a severe allergic reaction which causes swelling in the throat or mouth, cough, wheezing, noisy breathing, or shortness of breath can develop. This should be treated as a medical emergency.8


Most Babies Outgrow A Milk Allergy As They Get Older

Though cow’s milk allergy is not uncommon in babies, most of them tend to outgrow it by the time they’re 5 years old.9

Some Degree Of Lactose Intolerance Can Develop As Your Child Grows Older

Lactase levels tend to be high during infancy and then decrease after the age of 3 to 5. This can lead to the development of lactose intolerance as a child grows older. In fact, lactose intolerance is quite common among adults – it can affect up to 70% of people with Asian, Native American, or African ancestry and less than 20% of those with Anglo‐Saxon or Scandinavian ancestry.10


Remove Cow’s Milk From Your Baby’s Diet In Case Of Milk Allergy

For a baby with cow’s milk allergy, you will need to remove cow’s milk from your baby’s diet. And do keep in mind that most babies who are allergic to cow’s milk will also react badly to sheep or goat milk. You can substitute formula that contains cow’s milk with breastmilk, hydrolyzed formula, soy formula, or amino acid formula – your doctor will be able to guide you on what’s best for your baby.

[pullquote]The American Academy of Pediatrics recommends that you refrain from feeding cow’s milk to a baby under the age of 1. It can contain higher amounts of nutrients such as potassium, sodium, and protein than are ideal for your baby and may also be difficult for them to digest.11[/pullquote]


For babies who are being breastfed, eliminating foods that the baby may be allergic to from the mother’s diet can be helpful. Speak to your doctor before making dietary changes so that you and your baby don’t fall short on nutrients. Also, make sure that your baby is assessed after 6 to 12 months to see if they’ve outgrown the allergy.12 13

Modulate Lactose Intake Depending On The Degree Of Intolerance

For a baby with lactose intolerance, the way you approach it will depend on the degree of lactose intolerance. Those with congenital lactase deficiency will need a lactose-free formula. But if the condition is not severe, that is, it doesn’t cause poor growth or dehydration you can usually continue to breastfeed. In some cases, your doctor may advise you to stop breastfeeding for a brief time. You can then give your baby lactose-free formula and gradually put them back on breastmilk or normal infant formula once symptoms cease.14 15