Choosing Lactose-Free Baby Formula

Father feeds baby lactose-free formula from bottle
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Lactose-free baby formula is a cow’s milk-based formula specially designed for infants with lactose intolerance. Lactose-free formula may be necessary if a baby has difficulty digesting the lactose that naturally occurs in cow’s milk. Even more rarely, infants might have a condition called galactosemia in which exposure to lactose-containing formulas can be life-threatening. 

There are many different types of infant formula, and it can be challenging to choose among them. If your baby has digestive problems, the decision can be even more confusing. Here are some things to keep in mind as you consider whether lactose-free formula is a good option for your baby. 

What Is Lactose-Free Formula?

Lactose-free formula is typically made from cow's milk that has been refined to remove the lactose and replace it with a different form of sugar. Rather than lactose as a carbohydrate source, lactose-free formulas use a corn-based source.

While neither lactose-free formula nor soy formula contains lactose, lactose-free formula is created from cow's milk and therefore contains cow's milk protein.

These formulas are not tolerated by babies who are truly allergic to the proteins found in cow's milk.

Low-Lactose Formula

Low-lactose formulas are not the same as lactose-free formulas. They still contain some lactose but at a lower dose. Low-lactose formula may be a good option to consider for babies who are gassy, fussy, spit up a lot, or have general discomfort.

Lactose Intolerance

Lactose intolerance is the impaired ability to digest the sugar lactose. To digest lactose, the body needs to produce an enzyme called lactase. Some babies don't produce enough of this enzyme. The incidence is unknown, but a permanent inability to make any lactase at all is rare.

Symptoms of lactose intolerance include:

  • Bloating, cramping
  • Diarrhea or loose stools
  • Gas
  • Nausea, abdominal pain

Primary Lactase Deficiency

Some babies cannot produce enough lactase in the long term, which is known as primary or congenital lactase deficiency. This condition occurs when babies are born without the enzyme lactase and is caused by inheriting a gene from each of their parents. 

Primary lactase deficiency is extremely rare. Babies with this condition require a specialized formula, such as soy or lactose-free formula.

Secondary Lactase Deficiency 

Infants and children sometimes experience a temporary reduction in lactase availability, known as secondary lactase deficiency. This condition can occur after a bout of diarrhea that damages the lining of the intestine. Rotavirus and Giardia are two common organisms that can damage the intestines and cause temporary lactose intolerance. Crohn’s disease and Celiac disease can also cause it.

Premature babies can have developmental lactase deficiency. This is a temporary condition that lasts for a short time after birth. These infants are usually able to tolerate lactose eventually.

Temporary lactose intolerance usually doesn't require a switch to lactose-free formula. Once the underlying conditions are treated, lactose intolerance will usually resolve.


Galactosemia is a rare condition in which an infant cannot break down the sugar, galactose, which is part of the larger sugar, lactose. Mutations in a gene that affect the enzymes that break down galactose cause the condition.

There are several types of galactosemia:

  • Classic galactosemia (also known as Type I): Most common and most severe form, which can be life-threatening if not treated with a low-galactose diet
  • Galactokinase deficiency (also known as Type II): Causes fewer medical problems than classic, but infants can develop cataracts
  • Galactose epimerase deficiency (also known as Type III): Varies from mild to severe and can include complications such as cataracts, delayed growth, intellectual disability, liver problems, and kidney problems

Type I affects 1 in 30,000 to 60,000 babies. Types II and III occur even less frequently. The condition is diagnosed at birth through newborn screening tests or clinical symptoms such as feeding problems, jaundice, and sepsis. Babies with galactosemia cannot tolerate breastmilk and must consume lactose-free formula that is not derived from cow's milk. 

Other Tummy Troubles 

Lactose intolerance is not responsible for all tummy troubles in infants. Allergies, reflux, and colic are all things that may cause discomfort for your baby. Sometimes it takes some detective work to determine the cause of the problem.

Cow’s Milk Allergy

Cow's milk is one of the top allergens for children. However, this allergy is typically because of the protein in milk and not the lactose (sugar). A milk-protein allergy may be present at birth or can develop as a child grows. Lactose intolerance is more common in children 2 years old and above.

The symptoms of a milk-protein allergy include:

  • Diarrhea
  • Hives
  • Irritability
  • Runny nose
  • Vomiting

Parents sometimes confuse the symptoms of a milk-protein allergy with those of colic, gas, or other common digestive issues in babies.

More severe reactions to milk protein include swelling of the lips, tongue, and throat, and anaphylaxis. If your baby is having a severe reaction to a potential allergen, call 911.


Babies with reflux spit up small amounts of milk after they eat. Reflux is common, occurring in more than half of infants. Most of the time, spitting up is a regular occurrence that doesn’t result in pain or crying. Sometimes, though, it is more severe.

Gastroesophageal reflux disease (GERD) occurs in less than 1% of infants. A weak valve at the upper end of the stomach causes GERD. Overfeeding tends to trigger it. 

Symptoms of GERD include:

  • Choking on spit-up
  • Heartburn, observed as discomfort and crying
  • Poor weight gain

Reflux is treated with diet modifications in the breastfeeding parent (if breastfeeding), smaller and more frequent feedings, keeping baby upright, burping, and sometimes medication. Unless your baby is having other symptoms of cow’s milk intolerance, switching formulas may not help.


Colic is a term used to describe bouts of inconsolable crying in babies. Colic is characterized by crying that lasts longer than three hours a day, more than three days a week, and that lasts longer than three weeks. It affects between 10% and 40% of infants. The cause of colic is unknown.

While there is no definitive treatment for colic, your doctor may suggest that you try different things to see if they help. Options like probiotics, medication, and switching to hydrolyzed formulas may help.

It can be difficult to differentiate between conditions that can cause similar symptoms in infants. Consult your pediatrician to help diagnose allergies, sensitivities, or colic.

Using Lactose-Free Formula 

If your doctor has suggested that lactose-free formula may be a good option for your baby, there are plenty from which to choose. Most major formula manufacturers make specialized formulas for babies with all types of needs. If you're unsure which type of formula is best for your baby, ask your pediatrician for a recommendation.

Some lactose-free formula options include:

  • Enfamil ProSobee 
  • Similac Soy Isomil 
  • Baby's Only Organic LactoRelief Formula 
  • Similac Pro-sensitive 
  • Enfamil Nutramigen

Be aware that hydrolyzed formulas, like Nutramigen, are expensive and may not be covered by assistance programs. It can also take some time to see results after switching from a regular cow’s milk formula to a lactose-free formula—up to one or two weeks.

If your baby has been diagnosed with lactose intolerance or galactosemia, you should also avoid other dairy products like cheese and yogurt when introducing solids. Talk to your doctor for guidance.

Frequently Asked Questions

What is in lactose-free formula?

Unless it is a soy-based formula, most lactose-free formula is made from cow's milk that has been refined to remove the lactose and replace it with a different form of sugar. Lactose-free formulas use a corn-based carbohydrate source.

Does lactose-free formula cause constipation?

Formula is thicker and harder to digest than breastmilk. If your baby is switching from breastmilk to lactose-free formula, you may notice that your baby’s stools are firmer. 

Additionally, if your baby had loose stools as a symptom of a milk protein allergy or lactose intolerance, you may see firmer stools when you switch to a lactose-free formula. Firm stools are not the same as constipation.

Is lactose-free formula dairy-free?

Unless the formula you choose is soy formula, lactose-free formula is made with cow’s milk. It is not dairy-free, but the cow’s milk is processed to remove the lactose.

A Word From Verywell 

As a parent, you want your baby to be comfortable and happy. It is challenging to have a baby that seems unhappy or unwell. Not only that, caring for a fussy baby can be physically and emotionally exhausting.

Identifying the underlying problem can take some detective work. Be sure to work with your child’s doctor to determine the cause and find a solution. If you and your doctor agree that a lactose-free formula is right for your baby, ask your doctor for help selecting one.

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Verywell Family uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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Additional Reading

By Jennifer White
Jennifer White has authored parenting books and has worked in childcare and education fields for over 15 years.