15 May 2026
Expert: Gary Falcetano, PA
Senior Manager, Global Medical & Scientific Affairs, Allergy
Thermo Fisher Scientific
Food allergy evaluation increasingly begins in primary care, where clinicians face rising prevalence alongside diagnostic uncertainty. Food allergies now affect up to 1 in 10 children and adults, underscoring that allergy is not just a pediatric condition. However, the gap between perceived and true food allergy remains substantial. While approximately 35% of patients self‑report a food allergy, only about 3.5% have a confirmed clinical allergy. This disconnect increases the risk of misdiagnosis, unnecessary food avoidance, and patient anxiety.
As the first point of contact, primary care providers (PCPs) play a critical role in early identification, appropriate food allergen testing, and informed referral. A history‑driven testing strategy, supported by specific immunoglobulin E (sIgE) blood testing when indicated, helps improve diagnostic accuracy and patient outcomes.
This Ask the Expert discussion focuses on the fundamentals of food allergy evaluation in primary care.
How should clinicians differentiate between food allergies, food sensitivity, and food intolerance?
Terminology around food reactions is often used inconsistently. “Food sensitivities” and “intolerances” are not immune-mediated and may result from enzyme deficiencies (e.g., lactose intolerance) or pharmacological effects (e.g., caffeine sensitivity). These reactions are typically dose-dependent and largely assessed through patient history and symptom patterns.
Food allergies, by contrast, are immune-mediated reactions involving immunoglobulin E (IgE) antibodies. Reactions occur when the immune system responds to specific food proteins, either whole allergens (e.g., milk, eggs, fish, peanuts) or individual allergen components within those foods.
A clinical food allergy diagnosis requires both:
- A consistent history of symptoms following ingestion
- Evidence of IgE sensitization via testing
Sensitivities and intolerances should be assessed through patient history and observation of symptoms after food ingestion. If symptoms are consistent with an IgE-mediated allergy, then clinicians should move forward with allergy diagnostic testing.
Why are food allergies becoming more prevalent in both adults and children, and when should PCPs consider testing?
Food allergy affects approximately 8% of children and up to 10% of adults, with prevalence rising across age groups. This trend likely reflects a combination of environmental exposures, microbiome changes, dietary patterns, and improved awareness.
In primary care, testing decisions should be guided by a clear clinical history suggesting an immediate hypersensitivity reaction. Key signs include:
- Urticaria (hives)
- Angioedema (swelling of the lips or face)
- Vomiting
- Wheezing
- Throat tightness
- Multi-system reactions occurring shortly after exposure
Consistency and reproducibility of symptoms are critical. Chronic or vague symptoms (e.g., isolated gastrointestinal discomfort, fatigue, headaches) are less likely to indicate an IgE-mediated allergy. Careful, history-driven evaluation helps avoid unnecessary testing and misdiagnosis.
What is the recommended approach to diagnosing food allergies, and how does blood testing fit in?
Diagnosing food allergy requires a comprehensive clinical approach that begins with a detailed patient history, including the type, timing, and reproducibility of symptoms following food exposure. No single test alone can diagnose food allergy; results must always be interpreted in the context of clinical presentation.
sIgE blood testing is a safe and accessible tool used to assess sensitization to suspected foods. In primary care, it is particularly useful when the clinical history suggests an IgE-mediated reaction and can help guide risk assessment and referral decisions. Importantly, sIgE testing identifies sensitization, not necessarily a clinical allergy diagnosis.
A clinical diagnosis of food allergy requires both evidence of sensitization and a consistent history of symptoms upon exposure. Test results should be used to support clinical decision making, guide risk assessment, and inform referral to allergy specialists when appropriate.
Labcorp’s Food Allergy IgE profiles with component reflex testing fit into this diagnostic workflow after a clinical history identifies suspected allergens. When a whole-allergen result is positive, reflex component testing evaluates specific allergenic proteins. This helps differentiate primary allergy from cross reactivity and assess the potential risk of systemic reactions, supporting more precise diagnosis, counseling, and management.