Dairy is one of the most common food intolerances in the UK, yet many people struggle for years before identifying it as the source of their symptoms. The challenge is that "dairy intolerance" is not a single condition — it can involve lactose (the sugar), casein (a protein), or whey (another protein), and each affects the body differently. Understanding which component causes your symptoms makes management much more targeted and effective.
When people say they "cannot tolerate dairy," they could be reacting to any of three different components. Identifying which one is key to managing your diet without unnecessary restrictions.
The most common form of dairy intolerance. Lactose is the natural sugar found in milk. To digest it, your body needs an enzyme called lactase. When lactase production is insufficient, undigested lactose ferments in the large intestine, producing gas, bloating, and diarrhoea.
Casein makes up about 80% of the protein in cow's milk. Some people have difficulty digesting casein, particularly the A1 beta-casein variant found in most conventional UK milk. Casein intolerance can produce symptoms that overlap with lactose intolerance but may also include more systemic effects.
Whey makes up the remaining 20% of milk protein. It is found in liquid form in milk and is concentrated in protein supplements and some processed foods. Whey intolerance is less common than lactose or casein intolerance but can cause similar digestive symptoms.
Symptoms can range from mild discomfort to quite disruptive. The table below covers the most frequently reported symptoms, grouped by the body system they affect.
| Body System | Symptoms | Typical Onset |
|---|---|---|
| Digestive | Bloating, stomach cramps, diarrhoea, excessive wind, nausea | 30 mins to 2 hours |
| Skin | Eczema flare-ups, acne, itchy skin, rashes | Hours to days |
| Respiratory | Nasal congestion, sinus issues, excessive mucus | Hours |
| General | Fatigue, headaches, brain fog, joint discomfort | Hours to days |
Note: If you experience swelling of the lips, tongue, or throat, difficulty breathing, or hives immediately after consuming dairy, this may indicate a milk allergy rather than an intolerance. Seek medical attention immediately.
Many dairy intolerance symptoms — particularly skin issues, fatigue, and headaches — can appear hours or even a day after consumption. This delay makes it genuinely difficult to connect cause and effect from memory alone. A food diary that records both what you eat and when symptoms appear is the most reliable way to identify the link.
One of the biggest challenges of managing a dairy intolerance is that dairy appears in a surprising number of UK foods where you might not expect it. Under UK food labelling law, milk must be highlighted in bold on ingredient lists — but you still need to know what to look for.
Look out for these terms on ingredient lists: casein, caseinate, hydrolysed casein, lactalbumin, lactoglobulin, lactose, whey, whey powder, milk solids, milk powder, buttermilk, ghee, curds. Under UK allergen law, these should be highlighted, but knowing the terms helps you scan labels quickly.
The UK market for dairy alternatives has grown enormously. Here are the most widely available options, along with their nutritional considerations.
Dairy-free cheeses and yoghurts have improved significantly in recent years. Look for options fortified with calcium and vitamin B12. Coconut-based yoghurts tend to have the best texture, while soya-based options offer more protein.
Dairy is a significant source of calcium, iodine, vitamin B12, and protein in the UK diet. If you reduce or eliminate dairy, the British Dietetic Association recommends choosing fortified alternatives and ensuring you get these nutrients from other sources. Consider discussing your diet with a registered dietitian, especially if eliminating dairy long-term.
The NHS recommends a food and symptom diary as one of the first steps for investigating a suspected dairy intolerance. Here is a structured approach that works well.
Before changing anything, spend two weeks recording everything you eat and drink, along with any symptoms. Note the timing of both meals and symptoms. This gives you a baseline to compare against and often reveals patterns you had not noticed.
Remove all dairy products from your diet for 2-4 weeks. This includes obvious sources (milk, cheese, yoghurt, butter, cream) and hidden sources (check ingredient labels for the terms listed above). Continue tracking your symptoms throughout this phase.
Gradually reintroduce dairy products one at a time, starting with small amounts. Try one dairy food every 3 days and record any symptoms. This helps you identify which specific dairy components you react to and how much you can tolerate.
NutraSafe can help you through this process by tracking your meals and symptoms in one place, making it easy to spot which dairy products cause reactions and which you tolerate well.
See your GP before starting an elimination diet if your symptoms are severe, if you notice blood in your stools, or if you are losing weight unexpectedly. Your GP can test for coeliac disease, milk allergy, and other conditions that may mimic dairy intolerance. They can also arrange a hydrogen breath test to confirm lactose intolerance specifically.
NutraSafe helps you log meals, scan ingredients for hidden dairy, and track symptoms — making your elimination and reintroduction process clear and effective.
Download Free on the App StoreThe most common dairy intolerance symptoms include bloating, stomach cramps, diarrhoea, nausea, and excessive wind — typically appearing 30 minutes to 2 hours after consuming dairy. Some people also experience skin issues (eczema, acne), headaches, or fatigue. Symptoms vary depending on whether you are intolerant to lactose, casein, or whey protein.
Lactose intolerance is a digestive issue caused by insufficient lactase enzyme — it causes discomfort but is not dangerous. A dairy (milk) allergy is an immune-mediated reaction to milk proteins (casein or whey) that can cause hives, swelling, breathing difficulties, and in severe cases anaphylaxis. Dairy allergy is more common in children and can be life-threatening, while lactose intolerance is more common in adults.
Around 5% of the UK population is estimated to have lactose intolerance, according to the NHS. However, some studies suggest the true figure may be higher, as many people experience mild symptoms without seeking a formal diagnosis. Prevalence varies by ethnicity — it is more common in people of Asian, African, and Middle Eastern descent.
Many processed UK foods contain hidden dairy including bread and baked goods (milk powder, butter, whey), crisps and flavoured snacks (milk powder, lactose), processed meats (milk proteins as binders), sauces and dressings (cream, butter), chocolate and sweets, and some medications. Always check labels for milk, lactose, casein, whey, and butter.
Lactose intolerance symptoms typically appear 30 minutes to 2 hours after consuming dairy. Casein and whey protein reactions can be more delayed, sometimes taking several hours to a day. The severity often depends on the amount consumed — many lactose-intolerant people can tolerate small amounts of dairy without symptoms.
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Last updated: February 2026