Milk allergy and intolerance

Cow's milk protein intolerance

There are several disorders classified under the category of cow\'s milk protein intolerance (CMPI) and the very similar condition, known as milk and soy protein intolerance (MSPI),these can include cow\'s milk (or soy milk) proteinallergy or intolerance, lactose intolerance and other rare conditions such colitis (which is not discussed in this article). Many of these terms are often used interchangeably when there\'s a reaction to milk, but they don\'t mean the same thing.

It can be difficult to tell these milk related disorders apart because some symptoms can be the same for all these disorders. There are also some obvious and subtle symptoms that are different for each disorder. To further complicate diagnosis many of these same symptoms can also be present in other conditions that are not related to the milk at all.

Milk allergy


Our immune system allows our bodies to fight off many different diseases that could cause us harm. Sometimes our body\'s defenses go wrong and our immune system fails to recognize milk proteins as being harmless. So when the protein enters our system, our immune system reacts against the protein to destroy it. It does this by producing a chemical called \'histamine\'. Histamine has many affects on different parts of our body which present as allergic symptoms (described further down).

According to Professor Erika Jensen-Jarolim and colleges at the University of Vienna, regular use of antacids can increase the risk of food allergies (this includes milk) developing.


Because babies\' immune systems are immature milk allergy is more common in infants and children than in adults. Milk allergy affects about 1 in 50 babies. A child is more likely to develop this kind of allergy if blood relatives also experience allergies, such as eczema, asthma or hay fever.

Fortunately, approx 1/2 of thechildren affected by a milk allergy will outgrow the problem by 1 to 2 years of age, and approximately3/4of children will have outgrown it by the time they\'re 3 or 4 years old. So they can then go back to drinking milk and eating dairy foods the same as other children.


Around 1/2 of the children affected by a cow\'s milk protein allergy are likely to develop allergies to 1 or more other foods as well, this includes soy based infant formula. Although it is recommended to delay the introduction of solids for all children until6 months of age, once solids are commenced additional care needs to be taken for children with milk allergies to avoid high risk foods for as long as possible.

The most common foods that trigger an allergic reaction besides milk are peanuts, eggs, and soy. Foods allergies can also occur with other nuts, fish, shellfish, rye, wheat, oats, berries, tomato, cucumber, white potato and mustard. Highly sensitive children can be allergic to a range of other foods as well.

Regarding symptoms

An allergy to milk usually begins to develop in the first few months of life.Formula fed babies are at greater risk of developing a milk protein allergy thanbreastfed babies because the majority of infant formulas are based on cow\'s, goat\'s or soy milk (all of which can potentially cause allergic reactions). It is extremelyrare forbabies to be allergic to human milk. However, breastfed babies can develop an allergic reaction to proteins which are transferred into breast milk frommilk and foods eaten by a nursing mother.

Once an allergy has developed (which often does not occur at first exposure but after repeated exposure) symptoms will present immediately or within two hours of coming into contact with the \'allergen\' (in this situation the offending milk protein - there are 20 different proteins in cow\'s milk).

The effects of \'histamine\', which the body produces in response to any allergen (not only milk proteins)produces symptoms which involve not only the gastro-intestinal tract but also the skin, nose, throat and lungs. (See \'Symptoms\' below for examples). Fortunately the majority of allergic reactions to milk are not serious. However, a tiny number of highly sensitive children can suffer extreme and even life threatening symptoms.

If a child has an allergy to milk proteins, symptoms will continue for as long as the child is exposed to the same proteins. Because a formula fed baby less than 6 months old relies solely on milk for nutrition, a milk allergy willresult in failure to gain weight. Dependant on the mother\'s diet, a breastfed baby with a cow\'s milk protein allergy is likely to struggle to gain sufficient weight while the mother continues to consume the milk protein from anysource (obvious orconcealed in other foods).

Symptoms will disappear when the offending milk protein is excluded from the child\'s diet. Where the child is formula fed, once her formula has been replaced with one which does not contain the same milk protein. In the case of a milk protein allergy in a breastfed infant, when all sources of dairy products are excluded from the mother\'s diet.


Diagnosis is usually based on symptoms, which disappear once the allergen is eliminated from the child\'s diet. Allergy tests (skin prick tests or RAST blood tests) may also provide assistance in making an accurate diagnosis, as they are almost always positive in these cases.

Milk intolerance


How and why milk intolerances occur is still not fully understood. One popular theory related toinfants\' immature digestive systems, which may notproduce enough digestive enzymes to break down all the protein in the milk. This allows poorly digested protein to enter the large intestine, where the normal bacteria present in the bowel, ferment the protein creating stomach and bowel symptoms. It is believed that for some, these poorly digested proteins then enter the blood steam and create allergy-type symptoms related to skin, nose, throat and lungs. (These symptoms are referred to as \'allergy-type symptoms\' when present day allergy tests provide negative test results).

It\'s now believed that milk protein intolerance is more complex than it first appeared and for those with allergy-type symptoms, it may involve the immune system after all. Many milk (and food) intolerances are likely to be reclassified as allergies in the future, when the underlying immune mechanisms are fully understood and the development of diagnostic tools to test for these become available.


Because of the difficulty in diagnosing milk protein intolerance, accurate figures are unavailable. However, it\'s suspected that up to 8% of infants could experience some degree of milk intolerance in the early months. Some specialists believe the figures could be even higher than this. The figure decreasing as children grow and their digestive system matures.


Foods that can commonly cause reactions associated with intolerance, in sensitive people include milk, cheese and yogurt, chocolate, egg, flavor enhancers, food additives and natural salicylates found in strawberries, citrus fruits and tomatoes.


Symptoms of milk intolerance mostly involve only the stomach and bowel (see \'Symptoms\' below for examples). However, symptoms involving the skin, nose, throat or lungs that mimic those of milk allergy, can also occur.

The onset of symptoms related to milk intolerance is often more delayed than that of an allergic reaction and is rarely as life threatening. Symptoms are often \'dose related\', with a little not causing a problem but a lot producing symptoms.


Present day tests used to diagnose allergies are of little benefit in diagnosing milk intolerance. A combination of detailed history and a process of elimination are often used to determine if milk protein intolerance exists.

Lactose intolerance

Milk allergies and intolerances arepoorly understood conditions, even among many health professionals.Cow\'s milk PROTEIN intolerance is often confused with LACTOSE intolerance, which isintolerance to lactose contained in milk. This confusion is probably due to the fact that cow\'s milk protein and lactose are both found in the same foods. To further add to this confusion a milk allergy or intolerance to milk protein can cause changes to the lining of the small intestines, whichthen result in secondary lactose intolerance.

Many of the symptoms that indicate a cow\'s milk protein intolerance and lactose intolerance are the SAME andit can be difficult to tell them apart. However, becausethe inherited formlactose intolerance rarely develops before the age of 4 years, thiswould mean thatlactose intolerance occurring before this age is eitherbe linked with a cow\'s milk protein intolerance or is a temporary condition following an episode of gastroenteritis.

One significant symptom of both cow\'s milk protein allergy and lactose intolerance is loss of weight. What is so often misdiagnosed as a cow\'s milk protein intolerance or lactose intolerance in breastfed infantsislactose overload (also known as \'functional lactase deficiency\').Lactose overloaddisplays almost identical gastric symptoms to lactose intolerance but iseasily differentiatedby the simple fact that the child gains good amounts of weight.

Symptoms of food allergy

Severe reactions which may result in floppiness in infants or anaphylaxis (shock) are rarely caused by milk allergy.

Skin reactions

  • Immediate rash around the mouth.
  • Swelling of lips, mouth, tongue, face or throat.
  • Generalized eczema on the trunk.
  • Eczema behind ears and in body creases, such as neck and elbows.
  • Scaly skin on cheeks, cradle cap.
  • Dry skin or skin cracks e.g. bottom of the ear lobe, corner of the eye.
  • Persistent diaper rash.
  • Hives.
  • Itchy red rash.
  • Allergic "Shiners" (black eyes).
  • Watery or itchy eyes.

Nose, throat and lungs reactions

  • Runny nose (clear, watery).
  • Nasal congestion - stuffy or blocked nose, causing difficulty with feeding (breast or bottle).
  • Sneezing.
  • Itchy nose.
  • Persistent cough.
  • Wheezing or shortness of breath.

Stomach and bowel reactions

  • Abdominal pain and bloating.
  • Cramps.
  • Vomiting.
  • Excessive gassiness.
  • Diarrhea (loose runny stools), mucous or blood in motions.
  • Failure to gain weight or weight loss.


  • Pulling away from or refusing the breast or formula.
  • Irritability or unsettled behavior.
  • Poor sleep patterns.

Symptoms relating to the skin, nose, throat and lungs are not limitedto milk or food allergies. Many people show these symptoms to basically any other \'allergens\', this could be from a bee sting, medications e.g. penicillin, pollens, house dust, animal hair or moulds.

Many stomach and bowel symptoms often associated with cow\'s milk protein intolerance can also be due to other conditions, such as gastro-intestinal infections ORfeeding management. Where eliminating milk from the diet does not relieve these symptoms, further exploration may be necessary.

Behavioral symptoms on their own are not diagnostic of an allergy or intolerance and can be due to a number of other possible causes not related to milk or food. (See infant colic.)

Onset of symptoms

Reactions can occur immediately or up to several days after exposure to cow\'s milk proteins. The timing of symptoms can help to tell the difference between a milk allergy and intolerance.

Early reaction

Symptoms can begin to develop within 45 minutes of exposure to cow\'s milk proteins. The reaction is either a measles-like rash or hives, facial swelling. The respiratory system can be affected in this group, causing wheezing or sneezing or itchy, red eyes. This reaction usually occurs after small volumes of cow\'s milk. Allergy tests (skin prick tests or RAST blood tests) will often provide positive test results for this group.

Slow reaction

Symptoms can begin to develop between 45 minutes and 20 hours after exposure to cow\'s milk proteins. Moderate amounts of milk are required to trigger this reaction. Allergy tests (skin prick tests or RAST blood tests) are only positive in about 1 in 3 children in this group.

Late Reaction

Symptoms can begin to develop up to 20 hours after exposure to cow\'s milk proteins. Large volumes of milk are required to trigger this reaction. Only 1 in 5 children with delayed reactions show a positive skin prick test.

When to see your doctor

If your child has any of the symptoms above or if you suspect your child may have a milk or food allergy, see your child\'s doctor. Diagnosis is a difficult enough process even for an expert. Trying to work it out the best method of dealing with a cow\'s milk protein allergy or intolerance on your own would be virtually impossible.


An allergic response after drinking of milk generally occurs within the first 2 hours. In nearly 60% of young children with suspected milk allergy/intolerance,milk reactions occur after that time, meaning they are more likely to be milk protein intolerant rather than allergic to the milk protein. Because milk intolerance does not involve an IgE (Immunoglobulin E) immune response, these children are unlikely to have positive results to present day allergy tests.

A thorough history of the specific symptoms, severity and time symptoms develop in relation to ingestion of the offending food can help to make a clinical diagnosis of an allergy or intolerance. In making a diagnoses a doctor will generally recommend a process of elimination, which if successful will make diagnostic testing unnecessary. Tests are normally only necessary where food other than milk is suspected because it is a relatively simple process to eliminate milk proteins.

Atopy Patch Test

This is an allergy test where a special "patch" of test material is placed upon the skin and the allergy response tested.

Skin prick test (SPT)

This is an allergy test where an allergen is placed and pricked onto the skin and any allergy response measured. This test can be carried out safely and reliably in children as young as three months of age.

Radioallergosorbent Test (CAP/RAST)

CAP/RAST blood tests measure antibodies to proteins called IgE (Immunoglobulin E). It also tests for milk proteins as whole or individual fractions of milk (casein, whey, and beta-lactoglobulin).

Elimination and challenge procedure

Milk allergy and intolerance can also be diagnosed by removing milk (and milk products) from the diet for a period of time then reintroducing it for one feed to see if it causes symptoms.

For a proper investigation, a detailed understanding of food composition is needed, such as that of an experienced dietician. Simple advice to avoid foods, such as dairy products can be misleading as many foods contain milk. If the full range of intolerances is not identified, symptoms may return at some stage when the child eats a food containing the problem substance.

IMPORTANT: Elimination and re-introduction of milk and its products should only be undertaken with medical advice, particularly in cases with severe symptoms.

Food & milk protein intolerance in breast fed infants

Milk or food intolerance in a breastfed infant is one of the most complex conditions to accurately diagnose. As a result of much confusion and misunderstanding about this condition, milk or food allergies arevery oftenmistakenly blamed as the reason for many breastfed babies\' irritability.

Babies can develop cow\'s milk protein allergy or intolerance even while they are exclusively breastfed, because cow\'s milk proteins can pass through breast milk. Breastfeeding is often the safest, least irritant and most nutritious diet for sensitive babies and continued breastfeeding should be encouraged where possible.

Present day diagnostic tests are limited in their capacity to diagnose all incidences of milk (or food) intolerance. To complicate diagnosis further,1/2 of babies with a cow\'s milk protein intolerance will also develop allergies or intolerance to one or a number of other foods the mother may eat.

Management of a cow\'s milk protein intolerance in infants requires far more than simplistic advice to "eliminate all dairy foods" because milk is a basic ingredient of many prepared foods and milk proteins may behidden inmany foods.

The risk of an incorrect diagnosis

For many breast feed babies, a diagnosis of cow\'s milk allergy in a thriving infant is often made by well meaning friends, family and health professionals, based on vague symptoms such as eczema, irritability, sleeplessness or gastric discomfort. Although, these can be symptoms of a cow\'s milk protein allergy or intolerance, they can also be due to numerous other more common (and easily corrected) reasons.

Sadly, manybreast feeding mothers who are mistakenly lead to believe their babies have an allergy to something they have eaten, if symptoms fail to settle as often occurs,feel compelled to make further more restrictive food eliminations and this could potentially compromisetheir ownhealth, which may then impact oncontinuation of successfully breast feeding.

When your child is struggling to gain weight

Where a child is highly sensitive to a particular food the mother has eaten, she will display obvious symptoms which can include skin rashes, respiratory difficulties or she will struggle to gain enough weight (or possibly lose weight).

An accurate diagnosis of milk or food intolerance often relies on a complicated process of elimination and challenge. Diagnosis is best left your child\'s pediatrician and any food avoidance should ONLY be done with medical or dietetic advice so that your nutritionis not compromised. (Also see When your baby\'s weight gain decreasesfor other reasons for declining weight.)

When your child is thriving

Parents often become concerned about milk or food intolerance simply because their child is IRRITABLE and WAKEFUL. Restrictions to a nursing mother\'s diet are rarely indicated, and are of questionable value, where a baby is thriving and symptoms are generally of a behavioral nature. Strict food restrictions in this situation are likely to cause more harm than good.

Gastric symptoms of gas and diarrhea in thriving healthy breastfed infants are often associated with a lactose overload (a condition which is often mistakenly diagnosed as lactose intolerance). Even spitting up is far more likely to be due tolarge feeds andsmall tummiesthana reaction to food or milk. (Also see our article on gastro-esophageal reflux.)

Where your breastfed baby is thriving and symptoms are mostly behavioral or linked to stomach ache, gas or watery stools, we suggest you explore the many more common reasons for these behaviors and symptoms to occur before going down the path of what could turn out to be unnecessary and unhelpful food restrictions. (See infant colic and infant gas for more information.)

Infant formula for cow's milk intolerant babies

Many babies who are allergic to cow\'s milk proteins will also be allergic to the protein contained in goat\'s milk and soy beans. As all infant formulas readily available on the market are based on cow\'s milk, goat\'s milk or soy beans, switching from one brand of formula to another rarely helps. For the cow\'s milk protein intolerant child a specialized formula may be necessary. Specialized formulas are only available on a doctor\'s prescription.

Unless your formula fed baby has BOTH chronic diarrhea and failure to gain weight it is unlikely his troubles are due toan allergy or intolerance to his current formula and changing formula is unlikely to make any difference. (See Infant colic for some of the many reasons for irritability; When your baby\'s weight gain decreases for reasons for declining weight;Hungry baby if your baby does not appear to be satisfied by his formula;and Diarrhea for some of the many other reasons for frequent watery bowel movements.)

1. Goat\'s milk formula

Some babies with who are sensitive to cow\'s milk can tolerate goat\'s milk formula. However, babies with a true cow\'s milk allergy are frequently unable to tolerate goat\'s milk as well.

2. Soy protein formula

Around 50% of babies who are allergic to cow\'s milk can tolerate soy-based infant formula. However, recent studies are now highlighting evidence which questions the appropriateness of offeringsoy infant formulato babies.

3. Partially hydrolyzed formula

Partially hydrolyzed formulas are available without a doctor\'s prescription and may prove useful where a child is \'at risk\' of developing an allergy (e.g. where family members have allergies) However, partially hydrolyzed formula are not recommended for cow\'s milk allergic children, once symptoms have developed.

4. Extensively hydrolyzed formula

Hydrolyzed formula can be used for babies with cow\'s milk allergy, when breastfeeding isn\'t possible and if soy formula is poorly tolerated. These are cow\'s milk-based formula that has been processed by breaking down the protein into smaller parts that are less likely to cause allergy. These specialized formulas require a doctor\'s prescription.

5. Amino acid based formula (elemental formula)

"Neocate" is not based on cow\'s milk. It\'s a totally non-allergenic extensively hydrolyzed formula that is completely broken down into amino acids. It can be helpful for the 10% of cow\'s milk allergic children, who continue to display allergic symptoms while on an extensively hydrolyzed formula (which can contain residual fragments of cow\' milk proteins). Neocate is only available on a doctor\'s prescription.

Can allergies be prevented?

Unfortunately there may be no way of totally avoiding the development of an allergy where a child has a tendency. The chances of a child developing an allergic reaction to cow\'s milk proteins is increased if blood relatives suffer with allergies such as eczema, asthma or hay fever.

During pregnancy

There\'s no conclusive evidence that avoiding particular foods during pregnancy is beneficial. Severe restrictions may affect the nutrition of the developing baby. Exposure to allergens while in the womb may help promote immune tolerance.

During the early months

  • There\'s some evidence that exclusive breastfeeding during the first 6 months appears to protect against the development of allergy and helps to enhance immune activity. If you are breastfeeding your need for calcium provided in dairy products is particularly great during this time, so it\'s not a good idea to restrict milk and dairy foods as a preventative measure.
  • Restrict exposure to cigarette smoke, house dust, mould and animal hair.
  • Delay starting solids until as close as possible to 6 months, when a child\'s digestive system has had time to mature a little. Delay the introduction of egg white until at least 12 months and nuts, seafood and other high risk foods until at least 24 months or longer.

How we can help!

Where your baby is healthy and thriving (i.e. gaining enough weight), there is a very good chance that the reason or reasons for his distress have nothing to do with milk allergy or intolerance.

Through a consultation at, we can help you to explore the many possible reasons for your baby\'s irritability, poor sleep patterns, tummy upsets and/or feeding difficulties.

If you would like more information about our consultation service click here.

Written by Rowena Bennett
RN, RM, RPN, CHN, IBCLC, Grad Dip Health Promotion and author of\'Your Sleepless Baby: The Rescue Guide\'.

Copyright 2003. All rights reserved. Permission from author must be obtained to reproduce all or any part of this article.

Added Nov 2003. Reviewed Aug 2008; Sept 2013.