Onion Sensitivity Test

What this test measures

Onion belongs to the allium family along with garlic, leek, and chives. Allergy to onion is relatively rare, and some people who react to raw onion tolerate it when cooked, since heating changes some proteins. Reactions may appear as skin symptoms, digestive upset, or in more serious cases, breathing difficulty.

The test measures onion-specific IgE in a serum sample. A single blood draw provides the sample, and the laboratory reports a quantitative antibody level or reactivity class. When the test is part of a food panel, each allergen is reported separately, which helps show whether reactivity extends to related alliums.

A positive result indicates sensitization, not a guaranteed allergy. Some people have antibodies without symptoms, and others react only to certain forms of the food. A healthcare provider interprets the result with the person's reaction history and any other allergy testing that was performed.

• Onion-specific IgE antibodies
• Total serum IgE
• Quantitative allergen-specific IgE level
• IgE reactivity class for onion
• Cross-reactive allium allergens
• Related food allergen markers within the same panel

Why people order this test

• Investigate symptoms after eating onion or onion-containing foods
• Check for sensitization as part of a food allergy workup
• Clarify whether onion itself is a likely trigger
• Follow up on skin or digestive symptoms linked to foods
• Provide objective information before a provider visit

How to prepare

No fasting is required for this test. A blood sample is collected from a vein, usually at the arm. Follow any specific instructions from the laboratory, especially if the test is bundled with other panels.

Understanding your results

Results are usually available within one to three business days. The report shows the onion-specific IgE level or reactivity class. An elevated value suggests sensitization, and a healthcare provider interprets it with your symptoms and history.