Glossary of common cow’s milk allergy terms

It’s easy to get overwhelmed by all the medical terms associated with cow’s milk allergy. We hope that the following list will help you understand some of the common words and phrases that you may have heard. Please ask your medical team for more information if you are unsure about anything.


Allergen. A substance seen as harmful by the body’s immune system. Allergens can be digested (such as cow’s milk protein), inhaled into the lungs (such as pollen) or injected (such as penicillin). Allergens are usually harmless but are capable of triggering a response that starts in the immune system and results in an allergic reaction.

Allergic reaction. Occurs when the body’s immune system overreacts to a harmless substance known as an allergen. Children with cow’s milk allergy have allergic reactions to cow’s milk protein, such as colic (due to cow’s milk allergy), hives, skin rashes and respiratory and digestive problems.

Allergist. A doctor who is specially trained to diagnose, treat and manage allergies and asthma. Also called an immunologist.

Allergy. A condition involving an abnormal reaction to an ordinarily harmless substance called an allergen, such as such as cow’s milk protein, pollen or house dust mites.

Amino acid. Compounds that link together to form proteins, including cow’s milk protein. Amino acids are the building blocks of proteins and are used to make proteins in the body.

Amino acid-based formula (AAF). A hypoallergenic formula made with amino acids, the building blocks of protein. An amino acid-based formula contains no milk protein chains. These formulas may also be called elemental because proteins are in their simplest form.

Anaphylaxis. A life-threatening allergic reaction involving the whole body. Symptoms — low blood pressure, irregular heartbeat, distressed breathing, intense stomach pain, vomiting and hives — usually occur within minutes of exposure to an allergen. Also called anaphylactic shock.


Bloating. A condition in which the belly feels full and tight and may appear swollen.

Blood test. A medical procedure sometimes performed to test for food allergies. A blood test for cow’s milk allergy involves sending a sample of your baby’s blood (taken at a doctor’s surgery) to a laboratory to measure the amount of antibodies that react to cow’s milk protein. Results can take several days or longer. Blood tests are only able to show sensitisation to a food substance and can therefore not be used to confirm the diagnosis of cow's milk allergy. They should always be performed by a doctor.


Casein. The main protein found in cow’s milk that can trigger an allergic reaction in children with cow’s milk allergy.

Colic. Unexplained crying in an otherwise healthy and well-fed infant. Colic tends to follow a pattern of threes: crying for more than three hours per day (usually in the evening), for more than three days per week, and for more than three weeks. Colic usually starts a few weeks after birth and improves by the third or fourth month.

Constipation. Infrequent bowel movements that are firmly formed stools and difficult for your baby to pass.

Cow’s milk allergy. A condition involving an abnormal reaction to cow's milk proteins. Mild to moderate allergic reactions to cow’s milk include colic due to cow’s milk allergy, reflux, diarrhoea, constipation, gas, skin rashes and upper respiratory problems. More severe reactions include breathing difficulties, rectal bleeding, hives or rashes, anaemia and anaphylaxis.

Cow’s milk protein. Protein components such as casein and whey that are naturally found in cow’s milk and products made from cow’s milk. Babies with cow’s milk allergy have allergic reactions to cow’s milk protein.


Dermatitis. See eczema.

Diarrhoea. Frequent watery, loose stools.

Dietitian. A healthcare professional with special training in food and nutrition who can help with dietary choices. Registered dietitians translate the science of nutrition into practical solutions for healthy living. Some specialise in paediatrics or allergy management.

Double-blind placebo-controlled food challenge (DBPCFC). A test that can be used to determine whether your baby has cow’s milk allergy. The test can only be performed by healthcare professionals and normally takes place in the practice. Your baby will be given a food containing cow’s milk (the suspected allergen) and a food that doesn’t contain cow’s milk (known as the placebo) at different times. You won’t know which food your baby is receiving (hence the term ‘double-blind’). Your healthcare professional will watch your baby for a period of time for any signs of a reaction to determine if it is cow's milk allergy or not.


Eczema. A skin condition that is characterised by red, dry, itchy skin. Eczema can be an allergic reaction. Eczema is common in babies and children and may appear as tiny red bumps on the face, scalp, hands or feet. The bumps may itch, ooze and crust over, or feel like dry, scaly skin. Atopic dermatitis is a type of eczema.

Elemental formula. See amino acid-based formula.

Elimination diet. A method used to help diagnose food allergy. The suspected food is eliminated from the diet and a doctor monitors symptoms to determine whether that food is causing allergic reactions. To determine whether an infant has cow’s milk allergy, breastfeeding mothers may eliminate milk products from their own diets after consulting a doctor. Formula-fed babies may be switched by a doctor to a formula that is hypoallergenic, meaning that it does not contain whole cow’s milk proteins.

Essential fatty acids. A type of fat necessary for health that can be obtained only through food.

Extensively hydrolysed formula (eHF). A hypoallergenic formula for infants containing cow’s milk protein that has been so thoroughly broken into pieces (what’s known as hydrolysed) that the immune system of most infants with cow’s milk allergy no longer recognise the cow's milk protein as harmful. Nutramigen with LGG® is an extensively hydrolysed formula for the dietary management of infants with cow’s milk allergy.


Food allergy. A condition involving an abnormal reaction to substances found in food or drink, such as cow’s milk protein. An infant who has a food allergy to cow’s milk protein may experience colic due to cow’s milk allergy, eczema, hives and respiratory and/or digestive problems.

Food challenge. See oral food challenge.

Food intolerance. A digestive-system response to a food or food additive. Symptoms may include gas, bloating, cramping and diarrhoea.


Gas. Air that forms in the intestine while food is being digested. This air is then passed through the rectum. When air gets trapped in your baby’s belly, you may notice that they are bloated, have a hard tummy or pass wind. You may also notice that they cry or become fussy.

Gastroesophageal reflux (GER). A digestive problem that causes complications because of digested food flowing back into the oesophagus. Babies who have GER may frequently spit up lots of liquid, arch away from the bottle or breast, or seem irritable during or after feedings. Also called reflux.

Gastroenterologist. A doctor who specialises in diagnosing and treating problems of the digestive system.


Hay fever. A condition in which the immune system reacts to outdoor or indoor allergens such as pollen or dust mites. Symptoms include watery or itchy eyes, runny nose, nasal congestion, sneezing and coughing. Also called allergic rhinitis.

Hives. Raised, often itchy, red welts on the surface of the skin that can appear as the result of the body’s reaction to certain allergens such as cow’s milk proteins. Hives typically occur soon after exposure to an allergen. Also called urticaria.

Hydrolyse. The process of breaking down a protein into smaller parts or fragments. Cow’s milk protein in extensively hydrolysed formulas for infants, such as Nutramigenw with LGG®, have been broken down into small pieces so they are less likely to cause allergic reactions in most infants with cow’s milk allergy.

Hypoallergenic. Unlikely to cause an allergic reaction.

Hypoallergenic formula. A formula for infants that has been specially designed to not cause allergic reactions in most infants. Hypoallergenic formulas for the dietary management of infants with cow’s milk allergy include extensively hydrolysed formulas, such as Nutramigen with LGG®, and amino acid-based formulas for severe allergies, such as Nutramigen PURAMINO.


Immune response. The way in which the body reacts to foreign substances. The response is originated by the immune system. Cow’s milk protein can trigger an immune response in babies with cow’s milk allergy.

Immune system. A complex group of organs and cells that defends the body against bacteria, viruses and substances that are perceived as harmful.

Immunoglobulin E (IgE). A class of antibodies produced by the immune system that triggers allergic reactions. IgE antibody levels are often high in children with an allergy.

Immunologist. See allergist.

Iron-deficiency anaemia. A health condition that occurs when the body doesn’t have enough healthy red blood cells to carry adequate oxygen to tissues. Signs of anaemia in babies include lethargy and poor appetite.


Lactobacillus rhamnosus GG (trademark LGG®). A widely studied friendly bacteria shown, in combination with Nutramigen, to support the dietary management of infants with cow’s milk allergy.

Lactose. A sugar naturally found in milk and milk products. Also called milk sugar.

Lactose-free formula. A formula recommended for infants who are unable to digest a natural sugar found in milk called lactose. Lactose-free formulas that contain cow’s milk protein would not be recommended for infants with cow’s milk allergy because they are not hypoallergenic and can cause allergic reactions.

Lactose intolerance. A condition in which the digestive system is unable to fully digest the lactose in milk. People who are lactose intolerant usually lack sufficient amounts of an enzyme called lactase that is needed to digest lactose. Lactose intolerance is rare in infants and toddlers and typically affects adults and school-aged children in certain population groups. Symptoms may include gas, bloating, cramping and diarrhoea.


Milk protein. See cow’s milk protein.

Milk sugar. See lactose.


Oral food challenge. A test used to diagnose food allergies. The process involves feeding a patient a very small amount of a possible food allergen (such as cow’s milk) and carefully monitoring for any signs of allergic reactions. An oral food challenge must never be undertaken without the advice of a doctor.


Partially hydrolysed formula. An infant formula comprised of partially broken down or hydrolysed cow’s milk protein. Although partially hydrolysed formulas are hypoallergenic, they are not suitable for the management of cow's milk allergy because the milk protein chains are still big enough to cause allergic reactions in children with cow’s milk allergy.

Protein. A nutrient composed of one or more long chains of amino acids, which are an essential part of all living organisms, especially as structural components of body tissues and as enzymes and antibodies.


Rash. See eczema or hives.

Reflux. See gastroesophageal reflux (GER).


Skin prick test. A medical procedure that tests for sensitisation. A skin prick test for cow’s milk allergy involves exposing a small area of your baby’s arm or back to cow’s milk protein, and then gently pricking the skin so the liquid is absorbed. If your baby is sensitised, the site will turn red or swell in about 20 minutes. The test should be prescribed and performed by a doctor.

Soy-based formula. An infant formula made with soy protein.


Urticaria. See hives.


Vomit. The forcing of stomach contents through the oesophagus and out of the mouth.


Wheezing. A high-pitched whistling sound that often indicates that a person is having problems breathing, perhaps due to an allergic reaction.

Whey. A protein found in cow’s milk that can trigger an allergic reaction in children with cow’s milk allergy.