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Is it a Cow Milk Allergy?

Signs of Cow’s Milk Allergy and the Formula Fed Baby

The majority of babies are fussy at times, but an excessively upset infant may signal a cow’s milk allergy.   Cow’s milk protein is commonly used as the basis for standard infant formulas and is one of the most common food allergies found in infants and children.

Cow’s Milk Allergy vs. Intolerance

There are some similarities and differences between a cow’s milk allergy and lactose intolerance. It is important to be able to recognize the symptoms of an allergy versus an intolerance.

A milk allergy occurs when the immune system mistakenly targets cow’s milk protein – allergen – as a threat. The immune response is serious and symptoms usually appear within the first few months of life, or often within days after introducing cow’s milk-based formula. If your infant is experiencing 2 or more of the following symptoms he/she may have a cow’s milk allergy.

  • Excessive crying and irritability
  • Projectile vomiting beyond typical mealtime regurgitation
  • Bloody, loose stools
  • Skin rash (eczema) or hives
  • Gassiness, bloating or cramping

Lactose intolerance is less common in infants and symptoms are also less severe. Lactose intolerance occurs when the body is unable to produce enough of the enzyme lactase to break down lactose, the natural sugar found in cow’s milk. It usually shows up in late childhood or adulthood, but can occur in infancy though it is extremely rare. Infants who are born before 34 weeks gestation or those with small bowel injury are most likely to experience lactose intolerance. The following are common signs of lactose intolerance.

  • Gassiness, cramping
  • Diarrhea after consuming cow’s milk or cow’s milk based formula
  • Constipation (fewer than 3 bowel movements/week over 2 or more consecutive weeks)


Being able to identify an allergy versus an intolerance is important when prescribing an infant formula for a patient who may suffer from one of these conditions.

Hypoallergenic formulas are recommended for babies with milk protein allergies. Soy formula is generally not recommended as many infants with cow’s protein allergy are often allergic to soy, too.

Two major types of hypoallergenic formula are available:

  1. Extensively hydrolyzed formula such as Similac Alimentum or Enfamil Nutramigen, have cow’s milk proteins that are broken down so they are less allergenic than whole cow’s milk protein found in regular infant formulas. Most babies with cow’s milk allergy are able to tolerate these type of formulas.
  2. Amino Acid-based formulas such as Elecare or Neocate contain protein which has been broken down even more than the partially hydrolyzed formulas to its simplest form – amino acids.  These formulas are recommended for babies whose conditions don’t improve after trying partially hydrolyzed formulas.

Babies with true lactase deficiency need a lactose-free formula.  Soy formula or a cow’s milk based lactose free formula is the appropriate choice for these infants.

It generally takes 2 to 4 weeks for symptoms to completely clear up. Infants should continue on the prescribed formula until his/her first birthday. Parents should then be encouraged to gradually introduce cow’s milk into their child’s diet. It is sometimes helpful to suggest starting out with offering 4 oz infant formula mixed with 2 oz cow’s milk and gradually lessening amount of formula and increasing cow’s milk over a period of a few weeks. The dietary guidelines for a 1 year old recommends a total of 16 oz cow’s milk or other dairy products daily.