Food allergies have become a prevalent concern in today’s world, affecting people of all ages. When it comes to diagnosing food allergies, a careful and comprehensive approach is essential. A combination of clinical assessment and specific allergy tests, such as skin prick tests, specific IgE blood tests, and provocation challenges, remains the gold standard for confirming or ruling out allergies as the root cause of health issues.
Skin Prick Tests and Blood Tests
Skin prick tests and blood tests (specifically IgE tests) are valuable tools for the diagnosis of food allergies. These tests can provide insights into the likelihood that a particular food is causing an allergic reaction. However, it’s crucial to note the differences between these two diagnostic methods.
- A skin prick test involves introducing small amounts of allergens into the skin through tiny pricks. It requires patients to abstain from antihistamines for five days before the test and provides results within a mere 10-15 minutes.
- On the other hand, a blood test (IgE test) requires a visit to the lab, and results may take a few days. The key advantage of blood tests is that patients don’t need to discontinue antihistamines before the test.
In the ever-evolving field of allergy diagnosis, newer blood tests known as ‘component tests’ have emerged. These tests not only provide information about the nature of allergies but also assess the risk of a severe reaction. Incorporating these advanced tests into the diagnostic process enhances our ability to understand and manage food allergies more effectively.
Navigating the complexity of food allergies
Understanding that food allergies is not a straightforward process is important; allergy tests do not offer simple ‘Yes/No’ answers about whether someone is allergic. Instead, they provide information about the likelihood of an allergy. Moreover, these tests do not measure the severity of an allergy. The interpretation of allergy test results must be done in conjunction with a clinical history, ideally by a professional experienced in using these tests.
It’s essential to recognise that food allergies can evolve over time. Revisiting diagnoses can reveal changes, allowing certain foods to be safely reintroduced into the diet. In adults, common food allergies often involve fresh fruits and vegetables, particularly in individuals with pollen allergies, a phenomenon known as Pollen Food Syndrome. Those who have experienced severe allergic reactions, like anaphylaxis, should seek evaluation by an allergist, as new triggers may emerge.
Food-Dependent Exercise-Induced Anaphylaxis
For some individuals, food allergies manifest specifically when certain foods are consumed before exercise, a condition known as Food-Dependent Exercise-Induced Anaphylaxis. Diagnosing this requires a detailed history and tests to pinpoint the potential trigger, often necessitating molecular diagnostic testing.
This blog was written by Professor Adam Fox – November 2023. Professor Adam Fox can be found on Instagram @DrAdamFox – where you can follow his dedicated account for additional insights and advice on children’s allergies, designed to keep allergy families well-informed and aware.