Can You Use Flonase Before Allergy Testing?
You should discontinue Flonase (fluticasone nasal spray) at least 3 days before allergy skin testing, though intranasal corticosteroids generally do not interfere with skin test results and there is no need to discontinue oral or inhaled steroids.
Key Evidence on Intranasal Corticosteroids and Allergy Testing
Intranasal corticosteroids like Flonase do not typically interfere with allergy skin testing. 1 The mechanism of action differs fundamentally from antihistamines—corticosteroids work by reducing inflammation rather than blocking histamine receptors, which are what skin tests measure. 1
Medications That DO Interfere with Skin Testing
The following medications must be discontinued before allergy testing:
Antihistamines (H1-blockers): Must be stopped for specific time periods depending on the agent 1
Tricyclic antidepressants (TCAs): Should be discontinued temporarily if clinically able, as they significantly interfere with histamine response (odds ratio 6.33 for negative histamine test) 2
Benzodiazepines: Should be discontinued if possible (odds ratio 5.01 for negative histamine test) 2
H2-antagonists: May cause minimal interference (odds ratio 2.91) 2
Intranasal antihistamines (e.g., azelastine): Must be discontinued for at least 48 hours before skin testing 3
Medications That Do NOT Interfere
The following can be continued:
- Intranasal corticosteroids: No need to discontinue 1
- Oral corticosteroids: No need to discontinue 1
- Inhaled corticosteroids: No need to discontinue 1
- SSRIs: Unlikely to interfere (97% had positive histamine controls) 2
- SNRIs: Unlikely to interfere (100% had positive histamine controls) 2
- Proton pump inhibitors: Unlikely to interfere (97% had positive histamine controls) 2
Practical Algorithm for Allergy Testing Preparation
Step 1: Identify Current Medications
Review all medications the patient is taking, focusing on those known to interfere with histamine response 1
Step 2: Discontinue Interfering Medications
- Stop H1-antihistamines 3 days before testing 2
- Stop intranasal antihistamines 48 hours before testing 3
- Stop TCAs, benzodiazepines if clinically feasible 2
- Continue Flonase and other intranasal/oral/inhaled corticosteroids 1
Step 3: Verify Adequate Washout Period
Ensure the patient has not taken interfering medications within the specified timeframe before proceeding with skin testing 1
Important Clinical Considerations
Blood testing (serum-specific IgE) is not affected by patient medications and can be used as an alternative when antihistamines cannot be discontinued. 1 This makes blood testing particularly useful when:
- The patient cannot safely discontinue antihistamines 1
- The patient has extensive dermatitis or dermatographism 1
- Immediate testing is needed and medication washout is not feasible 1
Skin testing remains more sensitive than blood testing and allows for direct observation of the body's reaction to specific antigens, making it the preferred method when feasible. 1
Common Pitfalls to Avoid
Do not unnecessarily discontinue intranasal corticosteroids before skin testing, as this may worsen allergic rhinitis symptoms without improving test accuracy 1
Do not confuse intranasal antihistamines with intranasal corticosteroids—the former (like azelastine) must be stopped 48 hours before testing, while the latter (like Flonase) can be continued 3, 1
Do not assume all nasal sprays are the same—only antihistamine-containing nasal sprays interfere with testing 1, 3
Verify the patient has actually stopped antihistamines when instructed, as non-compliance is common and will result in false-negative skin tests 1