Green Pepper Unripe (f263) IgE Biomarker Testing
It measures IgE antibodies to unripe green pepper to assess allergy sensitization, with convenient ordering and clear results through Vitals Vault/Quest.
With Vitals Vault, you have access to a comprehensive range of biomarker tests.
This test looks for IgE antibodies your immune system may have made against unripe green pepper (often listed as f263). It is a targeted “allergen-specific IgE” blood test that helps clarify whether green pepper could be part of an immediate-type allergy picture.
A positive result does not automatically mean you will react every time you eat green pepper, and a negative result does not rule out every kind of food reaction. Your history—what happened, how fast it happened, and how reproducible it is—matters as much as the number.
You can use this result to plan safer food choices, decide whether you need broader allergy testing, and track changes over time when your clinician recommends retesting.
Do I need a Green Pepper Unripe (f263) IgE test?
You might consider this test if you notice symptoms that start soon after eating green pepper or foods that commonly contain it (fresh peppers, salads, salsas, cooked dishes, spice blends). Immediate-type allergy symptoms can include itching or tingling in the mouth, lip or tongue swelling, hives, flushing, wheezing, cough, nausea, vomiting, or lightheadedness. If you have had trouble breathing, fainting, or rapidly spreading hives after eating, treat that as urgent and discuss emergency planning with your clinician.
This test can also be useful when your symptoms are milder but consistent, such as mouth itching or throat scratchiness that happens with raw produce. In some people, that pattern fits pollen–food cross-reactivity (often called oral allergy syndrome), where the immune system recognizes similar proteins in pollens and certain fruits or vegetables.
You may not need this specific test if your reactions are delayed by many hours, are mainly digestive without immediate symptoms, or occur with many unrelated foods. In those cases, other evaluations (including different labs) may be more informative.
Testing is most helpful when it supports clinician-directed care: it adds objective data to your story, but it is not a standalone diagnosis and should be interpreted alongside your symptoms and risk history.
This is a laboratory-developed, CLIA-validated allergen-specific IgE blood test; results indicate sensitization and must be interpreted with your clinical history, not used alone to diagnose food allergy.
Lab testing
Order Green Pepper Unripe (f263) IgE through Vitals Vault
Schedule online, results typically within about a week
Clear reporting and optional clinician context
HSA/FSA eligible where applicable
Get this test with Vitals Vault
Vitals Vault makes it straightforward to order a Green Pepper Unripe (f263) IgE test when you and your clinician want a focused data point to guide next steps. You can order directly, get your blood drawn through the Quest network, and view results in one place.
If you are unsure how to interpret the number, PocketMD can help you turn the report into an action plan. You can use it to review what “sensitization” means, decide what companion tests make sense for your pattern (for example, other food-specific IgE tests), and plan reasonable retest timing.
If your symptoms suggest broader allergy patterns, Vitals Vault can also support a more complete lab map so you are not guessing based on a single result.
- Order online and complete your draw through the Quest network
- Clear, plain-language result guidance with PocketMD
- Easy reordering for follow-up testing when your clinician recommends it
Key benefits of Green Pepper Unripe (f263) IgE testing
- Helps identify whether you are sensitized to unripe green pepper proteins (an IgE-mediated pattern).
- Adds objective context when symptoms happen quickly after eating pepper-containing foods.
- Supports risk discussion for immediate reactions, including whether strict avoidance is warranted.
- Helps distinguish possible IgE allergy patterns from non-IgE food intolerance patterns that this test will not capture.
- Can guide smarter follow-up testing (related foods, spices, or broader panels) based on your history.
- Provides a baseline you can trend over time if your clinician recommends monitoring sensitization.
- Pairs well with PocketMD so you can interpret results in context and plan next steps without guesswork.
What is Green Pepper Unripe (f263) IgE?
Green Pepper Unripe (f263) IgE is a blood test that measures allergen-specific immunoglobulin E (IgE) antibodies directed at proteins from unripe green pepper (Capsicum annuum). IgE is the antibody class involved in immediate-type allergic reactions, where symptoms can start within minutes to a couple of hours after exposure.
A key point is that this test measures sensitization, which means your immune system recognizes the allergen. Sensitization increases the likelihood of an allergic reaction, but it does not guarantee one. Some people have detectable IgE without symptoms, while others can have symptoms with low or even undetectable IgE depending on the allergen, timing, and the limits of testing.
Because peppers are part of a broader botanical family and share some protein families with other plants, symptoms can sometimes reflect cross-reactivity. Your clinician may consider your pollen allergy history, reactions to related foods, and whether symptoms occur mainly with raw versus cooked pepper.
IgE sensitization vs. clinical allergy
A “positive” IgE result means your immune system has made IgE antibodies that bind to green pepper proteins. Clinical allergy means you actually develop reproducible symptoms with exposure. Your reaction history, severity, and consistency are what determine real-world risk.
Why raw vs. cooked can matter
Some allergenic proteins are heat-labile, meaning they break down with cooking, while others are more stable. If you react to raw pepper but tolerate cooked pepper, that pattern can suggest a cross-reactive, often milder syndrome—although you should not test this on your own if you have had significant reactions.
What do my Green Pepper Unripe (f263) IgE results mean?
Low or undetectable Green Pepper Unripe (f263) IgE
A low result suggests you do not have measurable IgE sensitization to unripe green pepper on this assay. If your symptoms are convincing and occur quickly after exposure, a low result does not fully rule out allergy, because timing, recent avoidance, and test sensitivity can affect detection. Your clinician may consider testing related allergens, repeating the test later, or using a different evaluation approach depending on your risk.
In-range result (interpretation depends on the lab’s reference and your symptoms)
For allergen-specific IgE, there is not a single “optimal” number the way there is for nutrients or hormones. Many labs report values with categories (for example, negative/low/elevated) that reflect the likelihood of sensitization, not the severity of symptoms. If your result is in a low or borderline range, your history becomes especially important for deciding whether avoidance, additional testing, or supervised food challenge discussions are appropriate.
Elevated Green Pepper Unripe (f263) IgE
An elevated result means your immune system is sensitized to green pepper proteins, and the probability of an IgE-mediated reaction is higher—especially if you have had consistent symptoms after eating pepper. The number alone does not predict how severe a reaction will be, and it should not be used to “grade” risk without clinical context. If you have asthma, a history of anaphylaxis, or reactions involving breathing or blood pressure symptoms, discuss a safety plan with your clinician.
Factors that influence Green Pepper Unripe (f263) IgE
Your overall allergic tendency (atopy) can raise multiple specific IgE results, sometimes with unclear clinical relevance. Cross-reactivity with pollens or related plant foods can also contribute to a positive test even when symptoms are limited to mouth itching. Recent exposures, long periods of avoidance, age, and immune conditions can affect IgE levels over time. Medications like antihistamines generally do not change blood IgE results (they affect symptoms), but immune-modulating therapies may influence results and should be reviewed with your clinician.
What’s included
- Green Pepper (Unripe) (F263) Ige
Frequently Asked Questions
What does the Green Pepper Unripe (f263) IgE test measure?
It measures allergen-specific IgE antibodies in your blood that bind to proteins from unripe green pepper (Capsicum annuum). This indicates immune sensitization that can be associated with immediate-type allergic reactions.
Do I need to fast for a green pepper IgE blood test?
Fasting is usually not required for allergen-specific IgE testing. If you are combining this with other labs that do require fasting, follow the instructions for the full set of tests you ordered.
Can a positive f263 IgE result diagnose a green pepper allergy?
Not by itself. A positive result supports sensitization, but diagnosis depends on your symptom history and clinical assessment. Some people have positive IgE without reacting, and some reactions are not IgE-mediated.
Can I have symptoms with a negative Green Pepper Unripe IgE test?
Yes. Symptoms can come from non-IgE mechanisms (intolerance, irritant effects, reflux, food additives), from a different allergen in the meal, or from an IgE allergy that is not detected on a single test. If reactions are immediate or severe, review next steps with your clinician.
Is green pepper allergy related to pollen allergies or oral allergy syndrome?
It can be. Some people with pollen allergies develop mouth itching or mild swelling with certain raw fruits and vegetables due to cross-reactive proteins. Your pattern (raw vs cooked, seasonal symptoms, other trigger foods) helps your clinician interpret whether cross-reactivity is likely.
How often should I retest Green Pepper Unripe (f263) IgE?
Retesting is individualized. Your clinician may suggest repeating in 6–12 months if you are monitoring changes in sensitization, especially in children or when dietary exposure changes. If you recently had a new reaction, your clinician may also recommend broader testing rather than repeating the same single marker.
What other tests are commonly considered with a food-specific IgE like f263?
Depending on your history, clinicians may consider other food-specific IgE tests, total IgE, or testing for related foods/spices. In some cases, skin testing or supervised oral food challenge discussions are used to clarify whether sensitization matches real-world reactions.