Does my Baby or Toddler have a Milk Allergy or Lactose Intolerance?

AngelaRD, LDN, CBS

Read time: 8 minutes

What to know about the difference between a cow’s milk protein allergy and lactose intolerance in babies and toddlers:

  • What is lactose intolerance and how can it be managed in babies and toddlers?

  • Learn the difference between lactose intolerance and lactose overload in babies

  • Understand what a cow’s milk protein allergy is and how to help your baby or toddler eat while avoiding dairy.

Some babies can’t tolerate dairy, whether through the mother’s diet in breast milk, in formula, or once they’ve started solids. But how do you know if it’s lactose intolerance, a dairy allergy, or something else entirely?

Read on to learn how to figure out if your little one may be intolerant to lactose, or if their symptoms may indicate a milk protein allergy.

What is a lactose intolerance?

Lactose itself is the sugar naturally found in dairy products.1 People with lactose intolerance do not have enough of the enzyme lactase, which helps the body break down and digest this milk sugar. Without lactase, bacteria break down the excess lactose, creating more fluid and gas, which is where the symptoms of lactose intolerance come from.2

Symptoms of lactose intolerance include:

  • Gas

  • Bloating, cramping, abdominal pain

  • Diarrhea

  • Nausea or even vomiting1,2

Symptoms usually show up between 30 minutes and 2 hours after having dairy.6

What causes lactose intolerance?

A lack of the digestive enzyme lactase is sometimes genetic.2 Other times lactose intolerance may occur as a result of infections in the intestines or other illnesses such as Crohn’s disease, Celiac disease, or Irritable Bowel Syndrome; or as a temporary symptom of a virus your child may have.3,4

One of the most common causes of lactose intolerance, however, is the slow natural decline of lactase that happens over time.5 This may start to occur after the age of 5 years.

Premature babies born before 34 weeks may also experience temporary lactase deficiency.5 Though this normally improves fairly quickly.4

Babies born at full term usually have plenty of lactose since it is a primary component of breastmilk (just like all mammalian milks).5,7 For this reason, lactose intolerance is generally not common in babies, but may start showing up in toddlers sometime after the age of three years.1

Read more: Is Your Baby Reacting to Something in Your Breastmilk?

Diagnosis of lactose intolerance

If you suspect your little one has lactose intolerance, call their health care provider. Sometimes just a medical and diet history can help their doctor figure out if your baby is not able to digest lactose well.4 Other times, more tests may be needed.

Tests that may help identify lactose intolerance:

  • Hydrogen breath test. If your toddler is not able to digest lactose, there will be more hydrogen in their breath than usual.

  • Stool acidity. Taking a stool sample may help the doctor see if your little one is not digesting lactose. The stool will be more acidic.4

Treatment of lactose intolerance

If your baby or toddler is diagnosed with lactose intolerance, the best treatment is avoiding or limiting dairy products and choosing lactose free products when they are available.2

While lactose intolerance is very rare in babies, should you feel your little one has a problem with lactose there is no need to stop breastfeeding. Simply minimize dairy in your diet and continue to breastfeed. However, keep in mind that your baby’s symptoms might actually be ‘lactose overload’ or cow’s milk protein intolerance. Keep reading to learn more about these alternate diagnoses.

For a baby on formula, you may consider a low lactose (‘sensitive’) formula to see if that is helpful. The pediatrician can help guide this decision.

The good news is that most people who are lactose intolerant can in fact continue to drink or eat a certain amount of dairy without it causing symptoms.2 Some people may be able to have one serving of dairy, while others may tolerate a little more or less. Try different amounts to see if your toddler can still have a bit of dairy in their diet.

There are also dairy products that naturally have less lactose in them or are manufactured to be lactose-free which your toddler may be able to tolerate, including yogurt, cow’s milk, as well as hard cheeses such as cheddar or swiss. And of course, always be sure to provide your baby or toddler with foods in a texture they are developmentally ready to eat!

Read about: What Type of Milk Should my Toddler Drink?

What is lactose overload?

Some women overproduce breastmilk, causing their little ones to take in a high volume of milk before they’re able to get a decent amount of the fat from the feed.8 This may cause something called ‘lactose overload’, or too much lactose for baby’s little tummy to digest at one time.8

Many times, lactose overload is mistaken for lactose intolerance, but with some changes in breastfeeding this issue can be managed and resolved.8,9

Symptoms of lactose overload include frothy or explosive stools that are a bit smelly and more than 10 urine diapers per day.8,9 A baby with lactose overload may have good or even higher-than-average weight gain.9

Interestingly, a baby who is suffering from lactose overload may always seem hungry, even though they are gaining enough weight.9 This is because when baby is not getting enough fat, they are not registering the fullness and satisfaction that fat triggers in the brain.8

Management of lactose overload

The most important thing is to first figure out if oversupply is the main culprit. The help of a lactation consultant will be important to get to the bottom of lactose overload.

If oversupply is the issue, the lactation consultant may recommend block feeding for a few days.8,9 This will help baby more fully empty a breast and get higher-fat feeds. Once symptoms are relieved, it’s time to go back to regular breastfeeding.9

For some mothers, the issue is not oversupply but rather feeding on a schedule or not feeding often enough.8,9 All of these may allow the breasts to fill up too much and provide baby with too much lactose and not enough fat.

Be sure to feed your little one on demand, or when baby asks to feed.11 This is normally anywhere between 8 and 12 times per 24 hours depending on baby’s age.10

Read more:
Dealing with an Oversupply

Breastfeeding On Demand vs on a Schedule

What is a cow’s milk protein allergy?

While lactose intolerance is rare in babies, some little ones believed to have lactose intolerance may actually have an allergy or intolerance to the cow’s milk proteins whey and casein.

A cow’s milk protein allergy (CMPA or CMA) or intolerance (CMPI) happens when the body has an overreactive immune response to the protein, triggering an allergic reaction.12 CMA is one of the most common allergies in young children, affecting about 1 to 3% of babies and toddlers.13,14

Fortunately, most children will eventually outgrow this as they get older and their digestive and immune systems mature.16

Symptoms of a cow’s milk protein allergy

Reactions usually happen within 1 to 2 hours after being exposed to cow’s milk protein, whether from breastmilk, formula, or from eating it in a meal.13 Reactions may range from mild to life-threatening.

In babies, symptoms of a milk protein allergy may include:

  • Colic, crying

  • Gassiness, bloating, discomfort

  • Eczema

  • Blood or mucous in the stool

  • Frequent stools

  • Vomiting16

In toddlers, symptoms of a milk protein allergy may include:

  • Red, itchy hives on the skin

  • Coughing and wheezing

  • Swelling of the lips, tongue, or throat

  • Vomiting

  • Anaphylaxis12,13

Anaphylaxis is a severe and potentially life-threatening allergic reaction that can occur within seconds to up to 2 hours after exposure to an allergen.15 It can, among other things, cause a sudden drop in blood pressure and impaired breathing. If your child has known allergies, make sure you speak to your physician or allergist to get an emergency plan in place so that you are always prepared.

Wondering if your little one has lactose intolerance or a milk protein allergy? Reach out to our team of registered dietitians and lactation consultants for free! They’re here to help on our free to live chat from Monday – Friday 8am - 6pm (ET), and Saturday – Sunday 8am - 2pm (ET). Chat Now!

Diagnosis of cow’s milk protein allergy

If you feel your little one has an allergy, speak with their healthcare provider immediately. Their doctor will ask about their diet and when the symptoms tend to show up.

Tests that may help identify a milk protein allergy:

  • Skin prick test: usually done by an allergist

  • IgE test: a blood test that can help diagnose an allergy

  • Diet elimination: Taking out all dairy from the diet for 3 to 4 weeks to see if symptoms improve12

A diet elimination should be done with the help of a dietitian to ensure that your little one continues to get the nutrients they need for growth and development even when eliminating a food group.

Treatment for a cow’s milk protein allergy

Formula fed babies will likely need to switch to a non-dairy formula. Note that soy formula may or may not be a good alternative as some babies with CMA may also have a reaction to soy protein.16

When breastfeeding an infant allergic to cow’s milk protein, all dairy will need to be eliminated from your diet. When eliminating dairy, whether from your own diet or for an allergic toddler, reading labels is critical.

The following list includes some of the ingredients that indicate the presence of milk in the product:

  • Milk, cheese, cottage cheese, yogurt, sour cream

  • Lactose, lactulose, lactoferrin, lactic acid starter

  • Whey

  • Casein and caseinates

  • Curds

  • Milk by-products (like butter, ghee, and buttermilk)

  • Dry milk solids or powder, condensed or evaporated milk17

Getting the right nutrition while eliminating dairy

You may wonder how you or your child’s nutritional status may be impacted when foregoing dairy products. Fortunately, there are many foods that can supply the important nutrients that dairy provides, such as protein, calcium, magnesium, and vitamin D.18

First: Get plenty of other dairy-free foods!

All whole fruits, vegetables, legumes, nuts, seeds, meat, poultry, fish, grains, and eggs are dairy free. When it comes to meeting your and your child’s nutritional needs, choose a variety of these non-dairy-containing foods.

Food sources of calcium: Fortified plant-based milk alternatives, fortified orange juice, canned sardines and salmon with bones, fortified dairy alternatives such as a non-dairy yogurt, tofu, soybeans, spinach, kale.19

Read more: Why Calcium Matters for Babies, Tots, and Mama

Food sources of vitamin D: Salmon, fortified plant-based milk alternatives, fortified cereals, egg, canned light tuna, portabella mushrooms – but most importantly: sunlight!20

Read more: Why Vitamin D Matters for Babies, Tots, and Mama

Food sources of protein: Fish, poultry, meat, beans, legumes, peas, nuts, seeds, tofu, eggs, whole grains.

Read more: Protein: Getting Enough and the Best Sources

Second: Look for dairy alternatives

There are many non-dairy substitues on the market, such as coconut yogurt, plant-based milk alternatives such as almond- and oatmilk; and even vegan dairy-free butter! These allow you to still cook and bake dairy-free with ease, as well as enjoy dairy-like foods in your day.

If you are choosing a plant-based milk alternative, look for ones that are fortified with calcium and vitamin D.

Read more: What Type of Milk Should my Toddler Drink?

Reach out to your child’s healthcare provider

If you suspect that your child has lactose intolerance or a cow’s milk protein allergy, call their healthcare provider immediately. They can make sure you and your little one are getting the support you need and help you make informed decisions for moving forward. They may also recommend further testing or recommend your child be seen by an allergist.

Remember that if your baby does not have an allergy to milk protein, that lactose intolerance in babies is not very common. Check in with a lactation consultant to help determine if what your baby is experiencing may be lactose overload, and what to do if it is.

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Our Happy Baby Experts are a team of lactation consultants and registered dietitians certified in infant and maternal nutrition – and they’re all moms, too, which means they’ve been there and seen that. They’re here to help on our free, live chat platform Monday - Friday 8am - 6pm (ET), and Saturday - Sunday 8am - 2pm (ET).Chat Now!

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For more on this topic, check out the following articles and recipes:

Nutrients to look for at 6-12 months

Guidance when raising a child with food allergies

Introducing Major Allergens to your Infant

Does my Child Have a Food Allergy or a Food Intolerance?