Quick Facts
- Sample: Blood draw (serum)
- Fasting: Not required
- Turn-around: 2-5 business days. May take longer based on weather, holiday, or lab delays.
Benefits
- Fast, accurate results using ImmunoCAP™ technology with high sensitivity and specificity
- No skin irritation – ideal alternative to prick tests for those with sensitive skin
- Convenient online ordering with nationwide certified lab collection
- Requires only 0.3–0.5 mL of blood for testing
- Private and confidential clinical-grade testing
Who Is This Test For?
- People experiencing unexplained allergic symptoms after eating grapefruit or citrus
- Individuals with known food allergies looking to identify additional triggers
- Those considering allergen immunotherapy needing confirmed sensitization testing
- Anyone with a family history of food allergies seeking preventive insight
- People with oral allergy syndrome (OAS) or pollen-food cross-reactivity concerns
How It Works – Just 3 Steps
- Order online and visit any certified lab location for a quick blood draw
- Lab analyzes your serum using ImmunoCAP™ fluorescence enzyme immunoassay technology
- Receive results in 2-5 business days with actionable recommendations
FAQ
What does this test measure? IgE antibodies specific to grapefruit allergens that indicate immune system sensitization.
Is this better than skin prick testing? Blood testing avoids skin irritation and works even if you're taking antihistamines.
Can I eat grapefruit before the test? Yes, no dietary restrictions are needed—recent exposure won't affect results.
What if my results are positive? Discuss with a healthcare provider about avoidance strategies and emergency medication needs.
Do medications interfere with results? Most don't, but inform your physician if taking immunotherapy or corticosteroids.
How accurate are the results? Detection shows >85% diagnostic sensitivity when combined with clinical history (Mayo Clinic 2019).
More Details
What is the purpose of this test?
The Grapefruit Allergy IgE Blood Test measures immunoglobulin E (IgE) antibodies specific to grapefruit allergens in your blood. When your immune system encounters grapefruit proteins it considers harmful, it produces these antibodies, which can trigger allergic reactions ranging from mild oral symptoms to severe anaphylaxis. This test uses the ImmunoCAP™ method, a fluorescence enzyme immunoassay, to accurately quantify grapefruit-specific IgE levels and help diagnose potential allergies (Mayo Clinic Laboratories 2019).
Grapefruit allergies are often associated with oral allergy syndrome (OAS), where cross-reactivity occurs between pollen allergens and fruit proteins. The immune system mistakes grapefruit proteins for similar pollen allergens, causing histamine release and allergic symptoms.
Who would benefit from this test?
This test is particularly valuable for individuals experiencing unexplained symptoms after grapefruit consumption, those with existing food allergies seeking to identify additional triggers, and people considering immunotherapy who need confirmed sensitization testing. It's also useful for anyone with family history of allergies or those with oral allergy syndrome (Cleveland Clinic 2025).
Healthcare providers often recommend this test when skin testing is contraindicated or when patients prefer blood-based diagnostics for convenience and comfort.
When should I order a Grapefruit Allergy IgE Blood Test?
Order this test if you experience allergic reactions after eating grapefruit, including tingling or swelling in your mouth, digestive symptoms like nausea or diarrhea, skin reactions such as hives or eczema, or respiratory symptoms like congestion or wheezing. Reactions typically occur minutes to hours after exposure (MedlinePlus 2024).
Severe reactions may include anaphylaxis with symptoms like rapid pulse, swollen throat, low blood pressure, or loss of consciousness—requiring immediate medical attention.
How do I interpret the results?
Results are expressed in kilo units per liter (kU/L) or class scores indicating sensitization levels:
< 0.35 kU/L (Class 0):
- What it means: No sensitization detected
- Typical action: Unlikely allergic to grapefruit
0.35–0.69 kU/L (Class 1):
- What it means: Low sensitization
- Typical action: Monitor symptoms, discuss with healthcare provider
0.70–3.49 kU/L (Class 2):
- What it means: Moderate sensitization
- Typical action: Consider avoidance, prepare an action plan
3.50–17.49 kU/L (Class 3):
- What it means: High sensitization
- Typical action: Avoid grapefruit, carry emergency medication
17.50–49.99 kU/L (Class 4):
- What it means: Very high sensitization
- Typical action: Strict avoidance, emergency plan essential
> 50 kU/L (Class 5–6):
- What it means: Extremely high sensitization
- Typical action: Complete avoidance, consult an allergy specialist
Values ≥0.7 kU/L suggest increased likelihood of clinical allergy, but clinical correlation is essential as some people show sensitization without symptoms (NCBI 2020).
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 fasting is required for this test. Most medications don't interfere with results, but inform your healthcare provider if you're taking immunotherapy treatments or corticosteroids. You can maintain your normal diet and activities before testing (Mayo Clinic Laboratories 2019).
The blood draw requires only 0.3-0.5 mL of serum, making it suitable for most patients including children.
How often should I get tested?
Initial allergy evaluation:
- Once for baseline assessment
Monitoring known allergy:
During immunotherapy:
- As directed by your allergist
Changing symptoms:
- Test when symptoms worsen or improve
Children with allergies:
- Every 2–3 years (to monitor for potential outgrowing of allergy)
Why early detection matters
Food allergies affect approximately 8% of children and 4% of adults in the U.S., with early identification potentially reducing emergency visits by over 30% through preventive measures (American Academy of Allergy 2021). Early detection enables proper dietary management, emergency preparedness, and improved quality of life.
Identifying grapefruit allergy early helps prevent accidental exposure and allows for proper nutritional planning to maintain a balanced diet while avoiding trigger foods.
Related tests you may consider
IgE Food Allergy Basic Test, Serum - Mosaic Diagnostics Test Kit - Checks for allergic reactions to 26 common foods by measuring IgE antibody levels in the blood, helping identify foods that may cause symptoms like rashes, stomach issues, or breathing problems
Immunoglobulin E Blood Test, Total, IgE - Measures the total IgE antibody levels in the blood to assess the likelihood of experiencing allergic reactions.
Lemon Allergy Blood Test - Measures the IgE antibody levels to detect a lemon allergy.
