Food allergies affect millions of people worldwide. In Malaysia, common food allergens include shellfish, peanuts, tree nuts, fish, egg, milk and wheat. An accurate diagnosis is essential — eliminating foods unnecessarily can lead to nutritional deficiencies, while missing a true allergy can be life-threatening in severe cases.
Allergy vs Food Intolerance — Key Differences
These two conditions are often confused but are fundamentally different:
| Food Allergy | Food Intolerance | |
|---|---|---|
| Mechanism | Immune system response (IgE-mediated) | Digestive/enzyme problem — no immune involvement |
| Onset | Minutes to 2 hours after eating | Hours to days after eating |
| Severity | Can be life-threatening (anaphylaxis) | Uncomfortable but not life-threatening |
| Quantity | Even tiny amounts can trigger a reaction | Often dose-dependent — small amounts tolerated |
| Testing | Skin prick test, specific IgE blood test | Diagnosis by elimination diet and symptoms |
Symptoms of a Food Allergy
Allergic reactions typically involve multiple body systems:
- Skin: Hives (urticaria), flushing, swelling (angioedema)
- Gut: Nausea, vomiting, stomach cramps, diarrhoea
- Respiratory: Runny nose, wheezing, breathlessness
- Cardiovascular: Drop in blood pressure, rapid pulse (in severe reactions)
- Anaphylaxis: Severe, sudden reaction involving multiple systems — a medical emergency requiring immediate adrenaline injection
If you suspect anaphylaxis: Call 999 immediately. If you have a prescribed adrenaline auto-injector (EpiPen), use it immediately while waiting for emergency services.
How Food Allergies Are Diagnosed
Diagnosis involves a combination of history-taking and specific tests. A doctor or allergist will first take a detailed history of your symptoms, timing and suspected foods. Tests include:
| Test | How It Works | Best For |
|---|---|---|
| Specific IgE Blood Test (RAST/ImmunoCAP) | Measures IgE antibodies to specific foods in the blood | Broad initial screening; safe for all ages |
| Total IgE | Overall IgE level — elevated in allergic conditions | General atopic tendency assessment |
| Skin Prick Test (SPT) | Tiny amounts of allergen applied to skin; positive = wheal forms | Rapid, cost-effective — done by allergist |
| Oral Food Challenge (OFC) | Controlled ingestion of suspect food under medical supervision | Gold standard for diagnosis or ruling out allergy |
| Component-Resolved Diagnostics (CRD) | Tests for specific allergy proteins within a food | Predicting severity; distinguishing true allergy from cross-reactivity |
Understanding IgE Test Results
Specific IgE results are reported in kUA/L and classified by class (0–6). A higher class suggests greater sensitisation — but does not necessarily predict the severity of a reaction. A positive IgE test shows sensitisation, which must be interpreted alongside clinical history.
Importantly, a positive test without symptoms may not require food avoidance. An allergist will interpret results in context and may recommend an oral food challenge to confirm a true clinical allergy.
Managing a Food Allergy
- Strict avoidance of the confirmed allergen
- Carry a prescribed adrenaline auto-injector (EpiPen) at all times if at risk of anaphylaxis
- Wear a medical alert bracelet for severe allergies
- Develop an anaphylaxis action plan with your doctor
- Inform restaurants and food handlers of your allergy when eating out
- Consider referral to a registered dietitian to ensure nutritional balance when avoiding major food groups
Medical disclaimer: This article is for general health education only. Please consult a qualified doctor or allergist for personal medical advice.