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Lactose Intolerance vs Cow's Milk Allergy: What's the Difference?

by Intoleran Australia

 

You’ve got tummy pain, bloating or diarrhoea after your morning coffee, or bowl of ice cream … and you think – “I think dairy is the problem.”

You could be right! Dairy is often a food trigger for people – who experience gut symptoms of gas, bloating, tummy pain and often looser bowel actions.

 

The thing is when dairy “doesn’t agree” it isn’t always straight forward – as it can be caused by different underlying factors. This then directly affects management.

 

Some people react to the milk sugar – Lactose (otherwise known as a carbohydrate). Others react to the milk protein  - Casein or Whey.

 

Some use the phrase “milk intolerance” when they actually mean either lactose intolerance or cow’s milk allergy.

 

Understanding the difference matters, because the cause, symptoms, testing and treatment are not the same. (allergy.org.au)

 

What's Actually in Cow's Milk?

 

Cow’s milk contains three major nutrients by weight (macronutrients)

  • Protein: around 3.4g per 100mL
  • Carbohydrate: around 4.8g per 100mL, almost entirely as lactose
  • Fat: around 3.4g per 100mL in full cream milk

 

The term “milk intolerance” is often used casually by patients, families and sometimes even online content to describe any unpleasant reaction after having milk. But it is not a precise diagnosis.

 

In practice, people may use “milk intolerance” to mean:

  • Lactose intolerance — a problem digesting the milk sugar lactose
  • Cow’s milk allergy — an immune reaction to milk protein
  • A general feeling that milk causes digestive discomfort, without a confirmed cause

 

Because both can involve gut symptoms, they are often mixed up. But one is a digestive issue, while the other is an immune-mediated condition. (allergy.org.au)

 

What is Lactose Intolerance?

 

Lactose intolerance happens when the body does not produce enough lactase, the enzyme needed to break down lactose. When lactose is not properly digested, it passes into the bowel and gets fermented by gut bacteria, which can lead to symptoms such as:

  • bloating
  • abdominal pain
  • excess gas
  • nausea
  • diarrhoea
  • tummy rumbling

Lactose intolerance affects the gut only. It does not cause hives, swelling, wheeze or anaphylaxis. (allergy.org.au)

 

Who gets lactose intolerance?

All ages from babies to the elderly can develop lactose intolerance. Primary lactose intolerance relates to a reduction or absence of the lactase enzyme.

Secondary (more temporary) Lactose Intolerance often happens as a result of injury to the gut lining – often after a bout of gastroenteritis or another condition that affects the gut lining. (Better Health Channel)

 

How is lactose intolerance diagnosed?

 

A careful clinical history is important. Diagnosis may involve a trial of reducing or eliminating lactose for a period of time, with subsequent reintroduction. In some settings a doctor may arrange a hydrogen breath test. 

 

 

Foods to Avoid with Lactose Intolerance

 

People with lactose intolerance can often tolerate lower levels of lactose. That means many adults do not need to avoid all dairy completely.

 

Higher lactose foods often include:

  • regular milk
  • standard yoghurt
  • custard
  • ice cream

 

Lower lactose or usually better-tolerated options may include:

  • lactose-free milk
  • lactose-free yoghurt
  • hard cheeses such as cheddar
  • butter in small amounts

 

Many people are surprised to learn that hard cheese is naturally very low in lactose, so it is often excluded unnecessarily. (Better Health Channel)

 

With Lactose Intolerance:  The goal is usually to reduce lactose to a tolerated level, not automatically remove all dairy forever. Many adults can still tolerate up to 1 cup of milk daily, however tolerance does vary.  (Better Health Channel).

 

When extra support is needed, the enzyme Lactase can be taken in tablet form to reduce symptoms.

 

 

What is Cow's Milk Allergy?

 

Cow’s milk allergy is very different. It is a reaction to the protein in milk, not the lactose (carbohydrate). The main proteins in milk are casein and whey.

 

Cow’s milk allergy is most common in babies and young children, although it can persist beyond infancy in some cases. Symptoms can be:

  • Immediate, often IgE-mediated
  • Delayed, often non-IgE-mediated
  • Part of other allergic conditions such as FPIES or eosinophilic oesophagitis

 

Unlike lactose intolerance, cow’s milk allergy can involve more than just the gut. It may affect the skin, respiratory system and overall immune response. (allergy.org.au)

 

Symptoms of cow’s milk allergy vary depending on the type of allergy, but may include:

  • Vomiting and reflux like symptoms
  • diarrhoea
  • blood or mucus in stools in infants
  • eczema flare
  • hives
  • swelling
  • wheeze, cough
  • in severe cases, anaphylaxis

 

That is one of the biggest distinctions: lactose intolerance can be uncomfortable, but it does not cause anaphylaxis. Cow’s milk allergy can. (allergy.org.au)

 

How is cow’s milk allergy diagnosed?

Immediate or IgE-mediated allergy

 These reactions often happen within minutes, sometimes up to about 2 hours after ingestion. Diagnosis may involve:

  • a detailed history
  • skin prick testing
  • specific IgE blood testing

 

These tests are useful for IgE-mediated allergy, but not for non-IgE reactions (usually gut mediated). (allergy.org.au)

 

Delayed or non-IgE-mediated allergy

These reactions can develop hours to days later. Symptoms are often more subtle and mostly gastrointestinal. They cannot be diagnosed with skin prick or standard allergy blood tests.

 

For suspected non-IgE cow’s milk allergy, the gold standard is usually:

  1. remove cow’s milk protein completely
  2. monitor symptoms carefully
  3. reintroduce under guidance to confirm whether symptoms return

 

The Royal Children’s Hospital advises that when cow’s milk is the suspected trigger, improvement may not be seen until around two weeks. (Royal Children's Hospital)

 

 

What foods need to be avoided?

 

This is where management differs a lot.

 

The Australian Society for Clinical Immunology and Allergy (ASCIA) notes that lactose intolerance is different from milk allergy, and that lactose-free products are not the solution for someone with cow’s milk allergy. (allergy.org.au)

 

 

With Cow’s Milk Allergy:

All forms of cow’s milk protein usually need to be removed unless a doctor or dietitian advises otherwise. That may include:

  • milk
  • yoghurt
  • cheese
  • custard
  • cream, cream cheese, ice cream
  • butter
  • regular chocolate containing milk solids
  • packaged foods containing milk ingredients

 

ASCIA also notes that people allergic to cow’s milk protein often react to similar proteins in goat’s and sheep’s milk as well, therefore these should also be avoided especially in babies and children. (allergy.org.au)

 

 

What about soy and milk alternatives?

For adults, alternatives may include calcium-fortified soy, oat or almond milk, depending on tolerance and nutritional needs.

 

For children, it is more complex. Some infants and children with cow’s milk allergy may also react to soy, and replacement choices need to consider age, growth, energy, protein, calcium and overall nutritional adequacy. (Royal Children's Hospital)

 

This is why babies and children with suspected cow’s milk allergy should ideally be managed with guidance from a Paediatric Dietitian and doctor.

 

Many adults self-diagnose with a “milk intolerance” and cut out all dairy, when in reality they may have lactose intolerance or Irritable Bowel Syndrome (IBS), and still tolerate smaller amounts of dairy.

 

Here is a quick summary on the differences:

 

Lactose intolerance

  • Problem with digesting lactose, the milk sugar
  • Causes mainly gut symptoms of bloating and looser (sometimes urgent) stools
  • Usually dose-dependent – the more you consume, the worse it is
  • Does not cause breathing difficulties and mouth swelling or hives
  • Many people can tolerate lactose-free milk and some lower-lactose dairy foods (allergy.org.au)
  • Digestive Enzymes (Lactase) can provide relief from symptoms allowing individuals to eat regular dairy.

 

Cow’s milk allergy

  • Problem with the immune system reacting to milk protein
  • Can affect skin, gut, breathing and whole-body reactions
  • More common in babies and young children
  • May cause serious allergic reactions, including anaphylaxis
  • Requires avoidance of cow’s milk protein, not just lactose (allergy.org.au)
  • Digestive Enzymes wont work with milk allergy

 

Lactose Intolerance vs Cow's Milk Allergy: Key Takeaways

 

Lactose intolerance and milk allergy are commonly confused. They are however very different issues, caused by difference underlying factors (lactose intolerance is carbohydrate intolerance) whereas milk allergy involves reacting to the milk protein.

 

Many adults with lactose intolerance can tolerate smaller bouts of regular dairy, or use Digestive Enzymes (Lactase) to enable them to eat out more freely.

 

For children, especially infants, it is worth getting a proper assessment early. For adults, it is also worth checking whether you truly need to avoid all dairy, or whether a more targeted approach would relieve symptoms without compromising nutrition.

 

 

Useful links

 

https://www.betterhealth.vic.gov.au/health/conditionsandtreatments/lactose-intolerance

 

http://www.rch.org.au/uploadedFiles/Main/Content/allergy/Non%20IgE%20Food%20Allergy.pdf

 

 

 

Written by Karina Savage 

Lead Dietitian - Intoleran

 

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