What should you know about casein and lactose intolerance?

Casein is a protein found in milk. A casein allergy can cause immune symptoms such as hives, swelling, wheezing, vomiting or an itchy mouth or throat soon after exposure. Even a small amount may matter for someone with a confirmed allergy.

Lactose is the natural sugar in milk. Lactose intolerance occurs when the small intestine does not provide enough lactase to digest it, so bacteria ferment the undigested sugar in the bowel. Bloating, abdominal pain, gas and diarrhoea are typical. These symptoms do not by themselves prove a milk allergy.

Note which foods cause symptoms, the amount eaten, the delay before symptoms and whether lactose-free products change the pattern. Do not deliberately provoke a suspected allergy. A clinician can decide whether Food Intolerance Testing, allergy assessment or another evaluation is appropriate.

If lactose intolerance is diagnosed, some people can manage symptoms by adjusting portions, choosing suitable alternatives or using lactase products when advised. If dairy is restricted, Nutrition Counselling can help protect calcium, vitamin D, protein and overall dietary balance. A confirmed casein allergy requires a separate avoidance and emergency plan.

Get emergency help after dairy exposure if you develop breathing difficulty, throat swelling, widespread hives with dizziness, repeated vomiting or faintness. Those features suggest an allergic emergency rather than ordinary lactose intolerance. Follow any prescribed emergency plan and call emergency services for severe or rapidly worsening symptoms.

Ask whether your pattern fits lactose intolerance, milk-protein allergy or another digestive problem; whether testing is useful; which foods need restriction; and how to maintain nutrition. Ask which symptoms require emergency action and whether a dietitian referral would help.