Allergy testing and food intolerance: what to know

A clinician may use skin-prick testing, specific IgE blood testing or a medically supervised food challenge when an immediate food allergy is suspected. Food intolerance is usually assessed through a symptom and diet history, targeted tests where appropriate, and a planned elimination followed by reintroduction.

Food allergy involves the immune system and can cause hives, swelling, wheezing, vomiting or collapse, often soon after exposure. Food intolerance does not cause the same allergic immune response; it more often produces digestive symptoms such as bloating, abdominal discomfort or diarrhoea.

A positive allergy test shows sensitisation, but it does not prove that eating the food causes symptoms. Results need to be interpreted alongside what was eaten, how much, how quickly symptoms began and whether the pattern has happened again. Broad commercial IgG food panels are not a reliable way to diagnose either food allergy or food intolerance.

Keep a record of foods, ingredients, portion sizes, symptom timing, medicines and exercise around each episode. Bring packaging or ingredient lists when a processed meal may be involved. Do not deliberately retry a food that previously caused breathing difficulty, throat swelling, faintness or a widespread rapid reaction.

Avoid cutting out several food groups without guidance, because unnecessary restriction can make nutrition harder to maintain and can obscure the pattern. A clinician or dietitian can plan a focused exclusion and reintroduction, decide whether lactose or another specific test fits the symptoms, and help identify suitable substitutes.

Call emergency services immediately after eating if there is trouble breathing, throat or tongue swelling, a hoarse voice, faintness, confusion or rapidly worsening symptoms affecting more than one body system. Use prescribed adrenaline promptly according to your emergency plan, then seek emergency care even if symptoms improve.

Arrange a medical appointment for repeated reactions, persistent diarrhoea, ongoing vomiting, blood in the stool, unexplained weight loss, poor growth in a child or symptoms that restrict normal eating. These features may need assessment for conditions other than intolerance.

Ask which diagnosis fits the timing and type of reaction, whether testing is likely to change care, and whether medicines must be paused before an allergy test. Also ask how long any elimination should last, how to reintroduce foods safely, what nutritional replacements are needed and whether you should carry adrenaline.