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Dairy Intolerances & Allergies: Causes, Symptoms and Treatments

Dairy foods are of course any that derive, ultimately, from milk. The word owes its origins to the Old English word dǣġe, (pronounced with a soft ‘g’), which originally meant ‘baker’ before being extended to ‘dairy maid’.

Milk is a common source of digestive discomfort, but abnormal reactions to food fall into two distinct categories: allergies and intolerances. Of course, this principle also applies to most other foods. This can be a confusing revelation because so often in casual discussion we use the terms interchangeably. 

What is dairy intolerance?

A dairy intolerance is, simply put, difficulty digesting milk or other dairy foods. This difficulty results in a number of common, but unpleasant symptoms, which we will explore in more detail below.

So a food intolerance is centred in the digestive system. But allergies are centred in the immune system and so are a quite different form of reaction. 

The immune system of someone with a dairy allergy has become sensitised to certain foodstuffs or other substances and responds to them as though they were pathogens (disease-causing organisms). 

A type of antibody called immunoglobulin E or IgGE binds to molecules of the problematic substance and releases inflammation-inducing substances: most commonly the neurotransmitter histamine. It is this which in turn triggers the symptoms of an allergy. A neurotransmitter is a chemical which transmits signals between cells.

However, to make this situation more complicated, intolerances can also involve the immune system to varying degrees. Poor digestion may irritate the inner lining of our intestines and that in turn can cause a condition called ‘intestinal permeability’ or ‘leaky gut syndrome’, in which food molecules begin to attract a different kind of immunoglobulin G – IgG. Many food intolerance tests are focused on the detection of IgG antibodies.

Causes of dairy intolerance

The cause of any food intolerance can be hard to pin down. Many are temporary, coming and going as the person’s state of health declines or improves over time. Factors like stress and prescription medication may also play a role.

One form of dairy intolerance, however, has a clear genetic basis. Lactose intolerance is, technically speaking, the inability to digest the milk sugar lactose, because the person’s body does not produce sufficient quantities of the enzyme lactase. Humans originally evolved to only produce lactase during infancy, in order to digest their mother’s milk. There was little use for it after the child was weaned, so the ability to digest lactose declined in most people as they grew older, and eventually stopped. 

Then, however, prehistoric people living in some areas, including Europe, realised that milk made a valuable, calorie-dense food source, and the ability to digest lactose into adulthood then became a survival advantage. The ability to digest lactase spread among their descendents and in time, butter and cheese became dietary staples. But lactose intolerance remains the default in many parts of the world to this day.

 Meanwhile, the cause of dairy and other food allergies is equally uncertain. Genetics can play a role: many food allergy sufferers also develop other allergic conditions like eczema and asthma. Another popular theory for the emergence of allergies is the so-called ‘hygiene hypothesis’: this is the idea that without balanced exposure to pathogens in childhood, a person’s immune system will not be properly ‘primed’ or trained, and so begin to misfire, triggering a range of symptoms from the uncomfortable to the potentially life-threatening.

Common symptoms of dairy intolerance

Symptoms of dairy intolerance vary by individual but typically include:


Hives – medically termed urticaria – is a type of rash characterised by inflamed skin. It can be itchy or even sting.. Hives typically move around the body but rarely last for more than a few days or weeks. This condition tends to recur at random intervals.


Wheezing is caused by an obstruction or restriction of some kind in our airways when we breathe in and out. Just like asthma, dairy allergies at their worst can cause the throat to constrict or narrow, making breathing more difficult and causing us to wheeze.


What function does vomiting serve? Answer: the rapid expulsion of a substance the body perceives as hazardous or poisonous. As we saw before, people with lactose intolerance cannot digest lactose, so as unpleasant as it may be, vomiting the offending substance out is a natural response.

Swelling of the lips, tongue or throat

Some people with a dairy allergy experience swelling of their lips, throat or tongue after contact with problematic foods. This is caused by the release of the neurotransmitter histamine, which in turns triggers an inflammatory response. It can be an alarming experience, but fortunately swelling is typically confined to rarer and more severe cases.

Treatments and help for dairy intolerance

If you routinely experience uncomfortable symptoms after eating dairy foods, your first port of call should be your doctor in order to rule out the possibility that you may be prone to anaphylaxis, the most extreme and potentially life-threatening form of allergic reaction. 

If the results come back negative, count yourself fortunate. But you will still face the challenge of managing your symptoms. The first step to doing so is establishing that dairy is the real culprit. You could try a so-called elimination diet and cut all dairy foods from your diet to assess the results. This can be an effective approach but it requires time and planning. Alternatively a range of easy-to-use dairy intolerance tests and dairy allergy tests are available for use at home. Take a finger prick blood sample and submit this for a detailed laboratory analysis.

Ultimately, there is no cure for a dairy allergy or lactose intolerance beyond simply avoiding the triggers. But whatever sense of deprivation you may feel will be more than made up for by the simple joy of feeling a whole lot better. 

The situation is more complex with other forms of dairy intolerance. As we saw above, these can come and go, so dairy foods may not be permanently off the menu. Stay clear of milk, cheese and butter for now and work on improving your overall state of health. Optimise your diet, learn to manage stress and cut down on the bad habits that may have contributed to the development of these digestive difficulties.

To learn more about your potential intolerances you could the simple-to-use and inexpensive Health Hub food intolerance test. Exploring your body’s unique balance of reactions to different foods could unlock the door to real and lasting change for the better when it comes to your health. You will receive a full report setting out the reactions generated by your blood sample to no less than ten different food groups, including:

  • Casein (cheese protein)
  • Cheese
  • Goat’s milk
  • Cow’s milk
  • Sheep’s milk