Quick Facts
- Sample: Blood
- Fasting: No special preparation is required.
- Turnaround: 3-5 business days. May take longer based on weather, holiday, or lab delays.
What This Test Measures
This test measures the level of IgE antibodies specific to onion (Allium cepa) in your blood, reported under the biomarker F048-IgE Onion. IgE antibodies are produced by the immune system in response to specific proteins it identifies as harmful, and elevated levels can indicate sensitization to the substance being measured.
This is a single allergen blood test focused only on onion. It does not measure other foods, other members of the allium family, or any antibody class other than IgE. The sample is collected as a standard blood draw, and results reflect onion-specific IgE only.
Benefits
- Measures IgE antibody levels specific to onion (Allium cepa)
- Uses a simple blood draw with no special preparation needed
- Provides objective antibody data to share with your provider
- Focuses specifically on onion, not other allergens or foods
- Delivers results online within the stated turnaround window
Who Is This Test For?
- Individuals who have had symptoms after eating, touching, or smelling onion
- People who notice hives, itching, or stomach upset around onion exposure
- Those who react to raw onion, cooked onion, or both
- Individuals who experience symptoms within minutes to a few hours of exposure
- People wanting an objective IgE measurement to discuss with a healthcare provider
How It Works
- Order Your Test Online
- Visit a Local Lab
- Get Results Online
FAQ
1. What does this test measure, and how is it different from other food allergy tests?
This test measures IgE antibodies specific to onion (Allium cepa) only, using the biomarker F048-IgE Onion. Unlike broader panels that screen multiple foods at once, this is a single allergen test, so it provides information about onion sensitization specifically and does not report on any other food or antibody class.
2. Who should consider this test, and when?
Onion allergy symptoms can appear after eating, touching, or even smelling onion in raw or cooked form, and they can develop anywhere from minutes to a few hours after exposure. This test may be relevant for people who have noticed reactions such as hives, itching, stomach upset, or swelling connected to onion exposure and want an objective IgE measurement to discuss with a healthcare provider.
3. Do I need to fast or prepare for this test?
No special preparation is required for this test. You can proceed with your normal routine before your blood draw appointment.
4. How quickly will I get results?
Results are typically available in 3-5 business days, though this may take longer based on weather, holidays, or lab delays. You'll be able to access your results online once they're ready.
5. How should I interpret my results, and what if they are abnormal?
Your result reflects the level of onion-specific IgE detected in your blood, but it does not by itself confirm a clinical food allergy, predict how severe a reaction might be, or establish whether onion is safe or unsafe for you to eat. An elevated result means sensitization was detected, while a negative result does not guarantee that a reaction cannot occur. If your results fall outside the expected range, review them with a qualified healthcare provider, who can consider your symptoms, history, and any other relevant information before recommending next steps.
Disclaimer: Reference ranges may vary by laboratory. Listed ranges are general guidelines and may differ from those used by the performing lab. Always consult your healthcare provider for interpretation.
Pre-test preparation
No special preparation is required for this test.
Cross-Reactivity
Cross-reactivity can occur when the immune system recognizes proteins in one substance that closely resemble proteins in another, sometimes triggering a reaction to both. This test measures only onion-specific IgE as identified above, and it does not test for any of the additional foods or substances discussed below. The examples that follow are not an exhaustive list, and they are presented as possible additional considerations rather than confirmed allergies. Having onion-specific IgE does not mean you will necessarily react to another allergen listed here. Depending on your history, symptoms, or your healthcare provider's guidance, testing for related allergens may also be worth discussing.
- Other Allium vegetables (garlic, leek, shallot, chives): Research has identified a shared plant enzyme across Allium species that may be recognized by the same IgE antibodies, and cross-reactivity among these related vegetables has been documented in peer-reviewed studies.
- Peach: A possible relationship between onion and peach sensitization has been proposed in medical literature, though available evidence suggests this cross-reactivity is marginal rather than strongly established.
