Diagnosis and Tests for Allergic Rhinitis (Hay Fever)
Clinician Summary (Quick View)
Allergic rhinitis diagnosis involves a clinical correlation between previous history, current examination, and the objective investigation. The gold standard strategy involves targeted skin testing via skin prick or through an intradermal process and/or specific IgE blood testing, which are chosen based on the patient’s age, concurrent conditions, medication interactions, and test availability. In complicated or refractory cases, ancillary tests, including nasal cytology, nasal provocation, FeNO, and imaging, may be helpful.
Patient Summary
If you experience seasonal or year-round sneezing, itchy eyes, or a congested nose, your healthcare provider might suggest allergy testing to determine which substance (pollen, dust mites, pet dander, molds, or foods) is causing your allergic symptoms. The skin prick tests and blood testing to detect allergy antibodies are among the available tests. These evaluations, along with your history and exam, play a role in customizing treatment and prevention.
Why Testing Matters
•Identifies any particular allergens to avoid (environmental control)
• Recommends treatment options (e.g., antihistamines, nasal steroids, immunotherapy)
• Helps to prevent complications, including exacerbations of asthma and sinusitis
• The diagnosis distinguishes allergic rhinitis from infections or non-allergic rhinitis
Diagnostic Workflow for Allergic Rhinitis
- History and pattern of symptoms (seasonal vs perennial, triggers, family history, jobs/hobbies).
- Physical examination (nasal mucosa, eyes, skin).
- Basic testing choice: skin testing if possible; blood testing if skin testing contraindicated or impractical.
- Ancillary tests where needed: nasal cytology, nasal provocation tests, component-resolved diagnostics (CRD), imaging if sinus disease is suspected.
- Interpretation & management plan: correlate test results with symptoms before prescribing immunotherapy or avoidance plans.
Major Tests for Allergic Rhinitis Explained
Skin Prick Test (SPT)
This is the first-line test for inhalant allergens (pollens, dust mites, molds, pet dander), and many other food allergens.
In this test a small droplet of standardized allergen extract is placed on the skin (commonly on forearm or on back). The skin is then pricked and examined after 15–20 minutes.
Procedure & preparation:
- For this test fasting is not required.
- Anti-histamine drugs are usually stopped 3–7 days before testing. Steroids being topically used don’t generally affect results but systemic steroids must be discontinued before testing.
- While choosing site for testing, avoid severe eczema sites.
- The test should be performed by trained staff in clinic with emergency care available.
Interpretation of results:
- Positive: wheal (bump) and flare — size compared to histamine (control group).
- Negative control (saline) rules out irritant.
- Sensitivity & specificity: high sensitivity; positive predictive value is best when history matches test.
It is fast, inexpensive, and tests multiple allergens at once with a high sensitivity profile. This test is not suitable for patients with uncontrolled eczema, patients taking antihistamines or any other medications, and patients with a small risk of systemic reaction (rare).
Intradermal Testing
When the skin prick test is negative but clinical concern persists, then intradermal testing is used in which a small volume of diluted allergen is injected into the dermis (usually for venom or medication allergy).It is considered more sensitive than SPT for certain allergens, but on the other hand, its results sometimes have more false positives and have a higher risk of systemic reaction, so it must be used selectively.
Patch Testing
In this test, adhesive patches with allergen panels are applied to the skin (typically the back) for 48 hours to detect delayed (Type IV) hypersensitivity contact dermatitis rather than IgE-mediated rhinitis.It is used for suspected contact-allergen rhinitis/dermatitis from perfumes, latex, preservatives, or industrial exposures.
Specific IgE Blood Tests (sIgE)
This is an allergy blood test that measures the concentration of allergen-specific IgE antibodies in blood. It is used when:
- The patient is taking antihistamines or can’t stop other medications.
- Patient with severe eczema or dermatographism and is preventing skin testing.
- Young child patients (sometimes preferred).
- Pre-treatment allergy workup if systemic reaction risk is high.
It has the advantage of objective numeric results, safety, and being unaffected by antihistamines, but its sensitivity profile is lower than SPT for some inhalant allergens, as it may detect sensitization without clinical symptoms (false positive).
Total IgE
In order to diagnose immunological problems, parasite infections, and allergic reactions, a total IgE test counts all of the IgE antibodies in your blood. A patient needs a particular IgE test to determine which allergens he is allergic to because this test is not specific. After a healthcare professional draws a blood sample, a laboratory determines the overall amount of IgE antibodies present in that particular blood.
Component-Resolved Diagnostics (CRD)
This is an advanced blood test that measures IgE to specific allergen components (molecular allergens) rather than whole extracts.
It helps risk stratify for systemic reactions by differentiating between actual sensitization and cross-reactivity (e.g., pollen-related food allergy vs. true food allergy).
Nasal Cytology and Nasal Smear
In this test scraping or lavage of nasal mucosa is examined for eosinophils and neutrophils under microscope.
Clinically:
- Eosinophilia supports allergic inflammation (NARES).
- Helps differentiate allergic vs infectious or nonallergic rhinitis.
Nasal Provocation Test (NPT)
In this test controlled exposure of a suspected allergen is directed into the nasal cavity to document allergic response (sneezing, congestion, objective airflow measures).
This test is employed for research, occupational allergy confirmation, food-related nasal symptoms, and when skin/blood tests are equivocal.
It has limitations, as it requires a clinic setting with monitoring and must be used selectively.
Fractional Exhaled Nitric Oxide (FeNO)
It is a noninvasive breath test that measures eosinophilic airway inflammation; it is useful when asthma and rhinitis overlap, but it is more frequently used for asthma.
An increased FeNO supports the allergy phenotype and indicates type-2 eosinophilic inflammation.
Imaging and ENT Evaluation
Nasal endoscopy and sinus CT are recommended in cases of persistent sinus symptoms, probable sinusitis, and structural problems (polyps, septal deviation).
Skin Tests vs Blood Tests: Comparison Table
Feature | Skin Prick Test (SPT) | Specific IgE Blood Test |
Primary use | Detects immediate IgE-mediated sensitization | Detects specific IgE antibodies in blood |
Speed | Shows results in just 15–20 minutes | Shows results in days |
Sensitivity | Higher for inhalant allergens | Variable (slightly lower for some inhalants) |
Specificity | Good when correlated with history | May yield false positives |
Medication Interactions | Antihistamine drugs show interaction | Not affected by antihistamines |
Safety | Smaller risk of systemic reactions (performed under supervision) | Very safe (Supervision not required) |
Target | Multi-allergen screening, rapid clinic assessment | Patients on medications, severe eczema, children, when SPT not possible |
Cost | Usually less costly | Tends to be more expensive |
Pediatric Considerations in Allergy Testing
• Many childhood allergies manifest as eczema and nasal symptoms; cooperation and skin condition must be taken into account while developing a testing approach.
• When SPT is impractical due to severe dermatitis or in babies, blood tests are recommended.
• If a child has rhinitis and a potential food allergy, refer them to a pediatric allergist for a combined evaluation
Safety, Risks, and Pre-test Instructions
Pre-test: Antihistamines and antidepressants should be discontinued before the start of the test, while intranasal steroids can be continued. Testing should be avoided during acute infections.
During the test: During the test, the clinic settings must have emergency kits, including epinephrine injections; most reactions occur locally, while there are rare chances of systemic reactions.
Post-test: After testing, apply antihistamine creams or oral medicines if significant itching occurs.
When to Refer to a Specialist (Allergist/Immunologist/ENT)
The patient should refer to an allergist/immunologist or ENT specialist if:
• Persistent or severe symptoms occur despite therapy.
• Suspected occupational allergy.
• Unclear diagnosis after initial testing.
• Consideration of immunotherapy.
• Recurrent anaphylaxis or severe drug/food allergy history.
• Complex comorbid asthma or sinus disease.
Common Clinical Pitfalls in Diagnosing Allergic Rhinitis
Following are the most common clinical pitfalls:
- Over-reliance on test positivity without symptom correlation.
- Failure to stop antihistamines before skin testing.
- Misinterpretation of cross-reactivity; for example, pollen vs food pollen-related allergy.
- Using total IgE alone to diagnose atopy.
Frequently Asked Questions (FAQs)
- How is allergic rhinitis diagnosed?
Allergic rhinitis is diagnosed based on symptom history, physical examination, and allergy tests such as skin prick tests or specific IgE blood tests. - What is the most common test for allergic rhinitis?
Skin prick testing is the most commonly used test to detect IgE-mediated sensitization to pollens, dust mites, molds, and pet dander. - When are blood tests used instead of skin tests?
Specific IgE blood tests are used when skin testing is not possible, such as in patients on antihistamines, with severe eczema, or in very young children. - Do I need to stop medicines before allergy testing?
Oral antihistamines are usually stopped several days before skin testing, while intranasal steroids can often be continued. Always follow your doctor’s instructions. - When should I see an allergy specialist for testing?
You should see a specialist if symptoms are severe or persistent, diagnosis is unclear, asthma is present, or immunotherapy is being considered.