Lactose Intolerance vs. Dairy Allergy: Symptoms, Diagnosis, Living With

Written by WebMD Editorial Contributors

• Symptoms
• Am I More Likely to Have Dairy Allergy?
• Getting Tested
• Testing for Lactose Intolerance
• Testing for Dairy Allergy
• Living With Lactose Intolerance
• Living With Dairy Allergy
• More

Lactose intolerance and dairy allergy sound a lot alike. Many people think they’re the same thing. But, how they’re caused (and how they affect your body) are very different.

Lactose intolerance involves the digestive system: If you have it, your body doesn’t make lactase, the enzyme needed to digest lactose. That’s the sugar in milk. Instead of digesting normally in your stomach and small intestine, undigested lactose moves into your colon, where it’s broken down by bacteria and causes bloating and gas. It can be uncomfortable, but it’s not dangerous.

Lactose intolerance is common in adults – about 30 million Americans have it by age 20. It’s more common in people with Asian, African or Native American heritage and less common in people with a northern or western European background.

Dairy allergy involves the immune system: If you have it, your body reacts to the proteins in milk and other dairy products as if they’re dangerous invaders. It releases substances that cause allergy symptoms. This allergic reaction can be mild (rashes) to severe (trouble breathing, loss of consciousness).

Dairy allergy is one of most common allergies, especially in children. As many as 2 in every 100 children under 4 years old are allergic to milk. It’s even more common in babies.

Some symptoms of lactose intolerance and dairy allergy may be the same:

• Diarrhea
• Nausea; sometimes vomiting
• Abdominal cramps
• Bloating
• Gas

But dairy allergy can also cause a reaction in other parts of your body, including the skin and lungs:

• Rash
• Hives
• Swelling, often in the lips and face
• Wheezing
• Tightness in throat
• Trouble swallowing

There may be blood in the stool (poop) too, especially in babies.

Anaphylaxis is a serious, life-threatening allergic reaction and often begins minutes after you eat a food you’re allergic to, but sometimes it can happen hours later. It usually involves more than one symptom in more than one part of your body at the same time.

If you have a severe allergy or if you’ve ever had anaphylaxis in the past, talk to your doctor about carrying an injectable epinephrine (Adrenaclick, Auvi-Q, EpiPen, a generic auto-injector, Symjepi) to slow down or stop the allergic reaction.

You’re more likely to develop dairy allergy if:

• You have other allergies
• You have eczema
• One or both of your parents has a food or other allergy, like hay fever, eczema or asthma
• You’re young. Milk allergy is more common in children. As you get older, your digestive system is less likely to react to milk, but you’re likelier to have lactose intolerance.

First your doctor will take your medical history to understand your symptoms and how your body reacts to dairy foods. Then you’ll be tested to confirm whether it’s lactose intolerance or a dairy allergy.

Lactose tolerance test: You’ll drink a liquid that contains a lot of lactose. About 2 hours later, the amount of glucose (sugar) in your bloodstream will be measured. If your glucose level doesn’t rise, you’re not digesting the lactose in the drink.

Hydrogen breath test: You’ll drink a liquid that contains a lot of lactose. Then, the hydrogen in your breath will be measured at regular intervals. If you’re not digesting lactose, it will be broken down in your colon, releasing hydrogen that can be detected in your breath.

Stool acidity test: Babies and children who can’t be tested otherwise can have their stool tested for lactic acid caused by the breakdown of undigested lactose in the colon.

Skin prick test: A small drop of liquid containing the dairy allergen is placed under your skin on your forearm or back. If a raised bump surrounded by itchy red skin appears, a dairy allergy is likely.

Your doctor might have you take a blood test too, which measures the amount of certain antibodies in your blood.

Both tests can have “false positives.” You can test positive for an allergy even though you really don’t have it. Your allergist will explain the results.

If an allergy is still suspected but not confirmed, your doctor may have you take an oral challenge. You’ll be fed different foods that may or may not contain milk in increasing amounts to see if you react to food that contains milk.

Lactose intolerance is easily managed, mostly by limiting the amount of dairy food and drink you consume. You can also try lactose-reduced ice cream and milk, or take lactase enzyme supplements when you eat dairy products to help your body digest lactose.

If you have dairy allergy, you’ll need to avoid all dairy foods and other foods that contain dairy products.

Staying safe means reading food labels to see if milk or ingredients containing milk are included. Milk proteins are found in many foods you wouldn’t expect. Some canned tuna, energy drinks and even chewing gum contain them. And don’t eat lactose-reduced foods if you have dairy allergy. They still contain the milk proteins that can cause allergic reactions.

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Lactose intolerance vs. dairy allergy

Lactose intolerance is different from milk or dairy allergy. With a dairy allergy, an immune reaction leads to swelling, breathing problems, and anaphylaxis. Lactose intolerance is an inability to digest the sugars in milk products. It causes intestinal symptoms, such as bloating and diarrhea.

Lactose intolerance is when the body is unable to properly digest the sugars in milk. This can cause uncomfortable digestive symptoms. This differs from dairy allergies, which occur due to an immune response to the proteins in dairy products and can cause severe reactions.

As dairy products can both result in allergies and intolerances and may present with similar symptoms, some people may confuse the conditions. However, they are very different.

In this article, we will discuss the differences between lactose intolerance and dairy allergies.

People can have different types of reactions to foods, where symptoms may occur due to either an allergic response, such as a food allergy, or an inability to properly digest certain foods, such as a food intolerance.

Dairy products can be responsible for both allergies and intolerances.

A dairy allergy, or milk allergy, occurs when the immune system overreacts to the presence of proteins in milk. However, lactose intolerance is not an allergy because it does not involve the immune system.

Instead, a person lacks an enzyme known as lactase, which breaks down a sugar — lactose — that naturally occurs in milk and dairy products, such as cheese and yogurt.

Dairy allergies

A cow’s milk allergy is the most common food allergy in infants and young children. However, people can be allergic to other types of milk, such as sheep, goat, and buffalo.

When a person with a dairy allergy encounters products containing dairy, it results in their immune system overreacting.

There are two types of dairy allergy: Immunoglobulin E (IgE)-mediated and non-IgE-mediated.

IgE refers to a type of antibody that the immune system may produce after recognizing a foreign substance. The immune system mistakenly determines that dairy proteins are harmful and responds by releasing chemicals, such as histamine.

This release of chemicals causes the symptoms of an allergic response. An IgE-mediated response typically occurs immediately.

A non-IgE-mediated response involves other components of the immune system rather than IgE. These reactions do not appear as quickly as IgE-mediated reactions and usually cause gastrointestinal symptoms such as vomiting, bloating, and diarrhea.

This is often why some people may confuse a non-IgE-mediated dairy allergy with lactose intolerance.

Lactose intolerance

A person with lactose intolerance does not have an allergy, but rather they cannot digest the sugars present in milk. This typically occurs due to lactose malabsorption. This term refers to the small intestine producing insufficient levels of lactase.

Estimates suggest that roughly 2 in 3 of the world’s population experience lactose malabsorption.

These low levels of lactase result in difficulty digesting or absorbing lactose, which leads to digestive symptoms such as bloating, diarrhea, and gas.

Possible causes of lactose intolerance include:

• Lactase nonpersistence: This is when the intestine produces less lactase after infancy. Lactase levels get lower with age and a person may not show symptoms of intolerance until later childhood, adolescence, or adulthood.
• Congenital lactase deficiency: This rare condition causes a person to produce little or no lactase from birth.
• Injury: Damage to the small intestines, such as from Crohn’s or celiac disease, may cause a person to produce less lactase.
• Premature birth: In some children born early, the small intestine may not produce enough lactase shortly after birth. However, it usually produces more as the baby gets older.

The main difference between lactose intolerance and dairy allergy is that one is an allergy and the other is an intolerance. An immune reaction causes dairy allergy, and a lack of the enzyme lactase causes lactose intolerance.

Other differences between lactose intolerance and milk allergy include the timing and severity of symptoms.

For example, a milk allergy most often appears in the first year of life, while lactose intolerance typically appears later. Furthermore, a severe allergic reaction to milk can be life threatening, whereas symptoms of lactose intolerance can be mild or more severe discomfort and pain.

	Intolerance	IgE-mediated allergy	Non-IgE-mediated allergy
Development	Typically appears later in life but can be present from birth.	Usually present from birth and a person may outgrow the allergy.	Usually present from birth and a person may outgrow the allergy.
Onset	Symptoms usually appear later.	Symptoms appear soon after eating the food, usually within 2 hours.	Symptoms may take up to 48 hours to develop.
Amount	A person may be able to eat a very small quantity of dairy with no adverse reaction.	The person cannot tolerate even small amounts of dairy they are allergic to. Exposure to even a tiny amount of the food can produce a severe reaction.	Small amounts of the allergen will result in a response.
Exposure	A reaction will occur only if the person consumes dairy.	A reaction may occur if the person consumes a product with dairy. It may also occur if someone prepares food or drink in an environment that contains dairy.	A reaction will also occur if a person consumes dairy or a food or drink item from an environment containing dairy.
Effect	Reactions can be extremely unpleasant but are rarely life threatening.	Severe and potentially life threatening reactions that can include anaphylaxis (anaphylactic shock).	Rarely life threatening as it is unlikely to result in anaphylaxis.

The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) advises that lactose intolerance may cause the following symptoms:

• gas
• bloating
• diarrhea
• nausea
• vomiting
• pain in the abdomen
• rumbling or growling sounds in the stomach

Symptoms can be mild or severe, depending on how much lactose a person consumes.

Initially, a doctor will ask someone about their symptoms, family and medical history, and diet. Then, they may perform a physical examination, which may involve checking for other conditions that can cause similar symptoms.

Sometimes a doctor will ask the person to avoid consuming dairy products for a while to see if symptoms subside.

A few tests are available to help a doctor diagnose lactose intolerance.

A hydrogen breath test involves consuming a liquid that contains lactose and breathing into a balloon-like container every 30 minutes over a few hours. If a person begins to experience symptoms and their hydrogen breath level increases, this suggests lactose intolerance.

Alternatively, a doctor may also measure a person’s blood sugar level before and after consuming a lactose solution. If blood sugar levels do not rise, this may indicate lactose intolerance.

Treating and managing lactose intolerance may consist of the following:

• dietary modification
• lactase supplementation
• treating an underlying condition in people with secondary lactase deficiency

Dietary modification

Some people may need to manage their diet to avoid symptoms. They may only need to limit the lactose they eat or drink, while others must avoid it altogether. The following foods and drinks can contain lactose:

• milk
• cream
• butter
• whey
• yogurt
• cheese
• some bread and other baked goods
• processed foods, such as breakfast cereals, flavored chips, and other snack foods
• processed meats

Lactase supplements

Doctors may advise a person with lactose intolerance to try lactase supplements. These products contain the enzyme lactase and can help to break down lactose. Typically, a person will take a tablet before they consume any food or drink containing lactose or add lactase drops to milk.

However, lactase supplements may not be suitable for some people, such as young children or pregnant people. Therefore, a person should check with their doctor before trying them.

Lactose intolerance and dairy allergies are different. Lactose intolerance is not an allergy because it does not involve the immune system — it is an inability to digest lactose.

People with lactose intolerance do not produce enough lactase to digest sugars in milk products. Conversely, dairy allergies are a reaction by the body’s immune system to dairy proteins. Dairy allergies often cause more immediate symptoms and may be life threatening if someone has a severe reaction.

If a person has symptoms when they consume milk and dairy products, they should see a doctor. The doctor can assess if they have an allergy or intolerance and suggest suitable treatment and management strategies.

What is the difference between lactose intolerance and cow’s milk protein allergy? such as anaphylaxis.

Terms such as suspected ‘milk allergy’, ‘milk intolerance’, and ‘lactose intolerance’ are often used without a clear understanding of the different meanings, understanding of the various mechanisms underlying them, or the dietary implications of the diagnosis. Treatments for these conditions are quite different, and misdiagnosis or treatment can have serious consequences for the patient.

Cow’s milk intolerance

Milk intolerance is caused by lactose intolerance, which occurs due to a deficiency of an enzyme called lactase, which is responsible for the breakdown of this sugar (lac toses) into its two main components: glucose and galactose. When lactose remains undigested because it has not been broken down, symptoms such as difficult digestion, flatulence, diarrhea, and abdominal pain appear. It is important to note that this condition is never the cause of rectal bleeding. The intensity and number of symptoms vary depending on the level of lactase deficiency and the amount of food eaten.

A distinction is made between primary lactose intolerance, where the levels of the enzyme lactase naturally decrease, which usually occurs after 3 years of age in some populations (eg, Africans and Asians). Lactase is also reduced or stopped produced in people who do not drink milk, since this enzyme is produced in the body solely to break down lactose. However, its production is restored due to the gradual introduction of milk into the diet.

Congenital lactose intolerance is very rare and occurs only in isolated populations such as Finns and Russians. Secondary lactose intolerance occurs as a result of damage to the villous intestinal epithelium of mucosal injury, usually after severe gastroenteritis. This intolerance is usually temporary in processes that alter the intestinal villi, such as intestinal infections or a gluten-containing diet in people with gluten intolerance, and disappears when the villi are restored to a healthy state.

Cow’s milk allergy

Food allergy is caused by proteins in milk. They act like allergens, causing an abnormal and exaggerated immune response in the body, producing specific antibodies against these foods. This is accompanied by the usual clinical manifestations of allergy, which manifest themselves at the level of the digestive, respiratory or skin systems and the intensity of which varies in each case.

Milk protein allergy can be either immunoglobulin E (IgE) mediated or non-IgE mediated. IgE-mediated reactions to casein, beta-lactoglobulin and/or alpha-lactalbumin usually occur immediately after ingestion, and clinical manifestations appear immediately, appearing a few minutes after ingestion of proteins due to the process of mast cell degranulation and the release of histamine and serotonin mediated these specific IgE antibodies directed against milk proteins.

Non-IgE-mediated allergic reactions are delayed and develop up to 48 hours, but still involve an immune system response. These are symptoms of a non-IgE-mediated disease, and are often mistakenly referred to as “symptoms of intolerance”, using either the terms “lactose intolerance” or “milk intolerance”. This condition often occurs in children during the first year of life. In this case, serum IgA levels are found above levels that would be expected, and clinical manifestations appear slowly and insidiously, with onset hours or even days after cow’s milk consumption. The condition typically presents with gastrointestinal symptoms (65%) that may affect the child’s nutritional status and/or skin symptoms (35%). Symptoms improve when cow’s milk protein is removed from the diet and reappear after repeated exposure.

Cow’s milk protein allergy is the third leading cause of food allergy after egg and fish allergies, and accounts for a quarter of all food allergies in children. There is a strong association between milk, peanut and egg allergies and atopic dermatitis. Allergy to cow’s milk protein is the most common allergy in young children. Most cases resolve spontaneously by the second or third year of life, and 95% of cases resolve by age 5.

The main risk factor is the introduction of cow’s milk proteins into the diet during the first months of life (with a maximum frequency at the age of 3 to 4 months), when the child should be exclusively breastfed. However, it can occur in exclusively breastfed infants (due to the small amount of protein passing from breastmilk if the mother consumes milk and/or milk derivatives) or in formula fed infants.

In the case of allergies in exclusively breastfed infants, the most allergic protein is beta-lactoglobulin, which does not exist in mother’s breast milk but passes into it in small amounts through the cow’s milk that the mother takes. This is manifested primarily by skin diseases such as eczema, urticaria and angioedema, asthmatic respiratory manifestations, abdominal pain, vomiting or diarrhea. The intensity and number of symptoms varies depending on the individual’s predisposition and the amount of protein consumed. Sometimes the first manifestation of an allergy in young children to cow’s milk proteins is the vagaries of breastfeeding, which sometimes can be the only manifestation without other clinical symptoms.

Gastrointestinal disorders and refusal of milk by the child cause long-term changes in the growth of the child, as evidenced by stunted growth and weight, turning into a true pathology that must be identified and treated as early as possible with the exclusion of cow’s milk proteins.

Treatment of lactose intolerance

The treatment of allergy and intolerance to milk protein consists in the exclusion from the child’s diet of cow’s milk and its derivatives: cheeses, yogurts, cottage cheese, creams, butter, custards, and some other processed foods that may contain cow’s milk proteins.

Children with suspected lactose intolerance usually do not need any testing and should improve within 48 hours on a low lactose diet. In secondary lactose intolerance, such as after severe gastroenteritis, lactose usually becomes tolerable again after about 6 weeks. The World Health Organization suggests that the infection must last for a minimum of 2 weeks to be able to affect lactose intolerance. Breastfeeding should continue despite the high lactose content of breast milk. If there is no enteropathy with damage to the small intestine causing secondary lactose intolerance, most infants with cow’s milk allergy can tolerate lactose well.

Cow’s milk allergy treatment

An infant with a suspected IgE-mediated cow’s milk allergy will need milk specific IgE testing (skin prick test or blood tests). Infants with suspected non-IgE mediated disease do not need these tests. Dietary treatment involves removing the allergenic protein from the diet. All dairy products should also be excluded from the diet of a nursing mother if a milk allergy is suspected in an infant and calcium supplements are prescribed. In formula-fed infants, the choice of formula is determined by the severity of the symptoms. Most babies respond well to highly hydrolyzed formulas that contain digested milk protein. The use of amino acid mixtures should be reserved for severe symptoms and those who do not respond positively to highly hydrolyzed mixtures.

An amino acid formula should also be used as the first line if supplemental nutrition is required in an exclusively breastfed infant who exhibits symptoms suggestive of an allergy to cow’s milk. The acquisition of tolerance in cow’s milk allergy should be assessed after at least 6 months of a milk protein-free diet.

Some other important facts about the milk allergy diet:

• – soy is not recommended before 6 months of age due to the fact that it contains isoflavones, which may have a weak estrogenic effect. There is also a risk of cross-reactivity: up to 14% of people with an IgE-mediated cow’s milk allergy also react to soy, as do up to 60% of people with a non-IgE-mediated cow’s milk allergy.
• – Rice milk is not recommended for children under 4.5 years of age due to arsenic content.
• – There is a cross reaction between mammalian milk. Goat milk and its products are not suitable for infants with cow’s milk allergy.

From the age of one, cow’s milk can be tried, provided that the first allergic reaction to cow’s milk was not an anaphylactic reaction. Drinking lactose-free milk does not solve the problem because it is milk from which the lactose has been removed, but its proteins remain intact.

These allergies usually resolve after the second or third year of life. They disappear at the age of one in 28-56% of cases, at the age of 2 in 60-77% and at the age of three in 71-87% of cases. The clinical tolerance of cow’s milk proteins is usually 95% at age 5. For this reason, it is important to gradually introduce milk and its derivatives into the child’s diet, since accustoming the child to these products guarantees the intake of calcium, which is necessary for the proper development of the bone and dental system.

Literature

Edwards CW, Younus MA. Cow Milk Allergy. [Updated 2022 Jun 27]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK542243/

Jensen SA, Fiocchi A, Baars T, Jordakieva G, Nowak-Wegrzyn A, Pali-Schöll I, Passanisi S, Pranger CL, Roth-Walter F, Takkinen K, Assa’ad AH, Venter C, Jensen-Jarolim E ; WAO DRACMA guideline group. Diagnosis and Rationale for Action against Cow’s Milk Allergy (DRACMA) Guidelines update – III – Cow’s milk allergens and mechanisms triggering immune activation. World Allergy Organ J. 2022 Sep 15;15(9):100668. doi: 10.1016/j.waojou.2022.100668. PMID: 36185551; PMCID: PMC9483786.

Walsh J, Meyer R, Shah N, Quekett J, Fox AT. Differentiating milk allergy (IgE and non-IgE mediated) from lactose intolerance: understanding the underlying mechanisms and presentations. Br J Gen Pract. 2016 Aug;66(649):e609-11. doi: 10.3399/bjgp16X686521. PMID: 27481986; PMCID: PMC4979917.

lactose intolerance and milk allergy difference

Lactose intolerance and milk allergy can cause similar symptoms, causing a lot of confusion, but they are not the same. How can you tell the difference and still maintain a balanced diet.

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Although both diseases require elimination of dairy products from the diet, they have different effects on the body. Lactose intolerance is a digestive problem; Allergy to dairy products is an immune system problem.

Article content

Lactose intolerance

Lactose intolerance affects the digestive system and has two main causes: lactase deficiency and lactose malabsorption. Lactase is an enzyme in the small intestine that breaks down the milk sugar lactose. Like many conditions, the severity of lactose intolerance varies from person to person. Most people can consume a certain amount of lactose without any symptoms, but the amount depends on the individual.

Dairy allergy

Dairy or cow’s milk protein allergy is an immune system problem that can be more serious and even life-threatening. Allergy to cow’s milk protein most often occurs in children, and approximately 2-3% of children under the age of three are allergic to milk. About 80% of children get rid of milk allergy by the age of 16.

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Symptoms

Some symptoms of lactose intolerance and dairy allergy may be similar:

• Diarrhea
• Nausea, occasional vomiting
• Cramping
• Bloating

900 67 Gas

Allergies may cause other symptoms:

• Urticaria
• Edema, often on the lips and face
• Problems with swallowing breathing

Diagnosis

It is not always possible to distinguish between these two conditions on your own, therefore it is necessary to undergo an examination by a doctor in order to make the final diagnosis.

Lactose intolerance can usually be distinguished from milk allergy by less severe symptoms and your history of dairy problems.

Tests you can take:

Lactose tolerance test

This test requires you to drink a liquid containing 50 g of lactose. Next, blood will be taken from you for glucose 20 minutes and 40 minutes after drinking and compare it with the initial glucose level before the test. If your glucose level does not rise, then you are not digesting lactose.

Hydrogen breath test

Again you need to drink a drink with lactose, after which you will measure the hydrogen content in the exhaled air. If it rises, then lactose is fermented in the intestines under the influence of the intestinal microflora, and the patient is diagnosed with lactose intolerance

Fecal pH test

Undigested lactose also increases the amount of acid in the stool. pH less than 5.5 indicates fermentation processes in the intestine. Most often, such a test is used for infants.

Food Allergy Testing

You may be referred to an allergist for a skin test or blood test for allergies

A genetic test does not diagnose lactose intolerance, it only shows a predisposition to developing it

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Living with lactose intolerance

Lactose intolerance is easily managed, mainly by limiting the amount of dairy products and drinks consumed.