Do you need to stop taking Singular (Montelukast) before an allergy test?

Discontinuation of Montelukast (Singulair) Before Allergy Testing

You do not need to stop taking Montelukast (Singulair) before allergy testing. Leukotriene receptor antagonists like montelukast do not interfere with skin prick testing or serum IgE measurements and can be continued during allergy evaluation 1.

Medications That Must Be Stopped

Antihistamines are the primary medications that interfere with allergy skin testing and must be discontinued 2, 1, 3. The specific washout periods are:

• Cetirizine: 5-7 days before testing 1
• Loratadine: 7 days before testing 1
• Fexofenadine: 3 days before testing 1
• Diphenhydramine: 3 days before testing 1
• Hydroxyzine: 7-10 days before testing 1

All second-generation H1-antihistamines should be stopped at least 3 days before skin testing to ensure positive histamine controls 4.

Medications That Can Be Continued

The following medications do not significantly interfere with allergy testing and can be continued 1, 4:

• Inhaled corticosteroids (ICS): Have minimal systemic effects and do not interfere with skin tests or serum IgE results 1
• Leukotriene receptor antagonists (montelukast): Do not suppress skin test responses 1
• SSRIs and SNRIs: Unlikely to interfere with skin testing 4
• Proton pump inhibitors (PPIs): Do not significantly affect histamine response 4

Type of Testing Matters

For serum IgE blood testing, antihistamines do not need to be discontinued because they don't affect laboratory measurements of IgE antibodies 1, 3. This is an important distinction from skin testing where antihistamines cause false-negative results by suppressing the histamine wheal response 2, 1.

Additional Medications to Consider Stopping

If undergoing skin prick testing, the following medications should also be temporarily discontinued if clinically feasible 4:

• Tricyclic antidepressants (TCAs): Significantly interfere with histamine response (odds ratio 6.33 for negative histamine test) 4
• H2-antagonists: May cause false negatives (odds ratio 2.91) 4
• Benzodiazepines: Interfere with skin testing (odds ratio 5.01) 4
• Certain atypical antidepressants: Quetiapine and mirtazapine should be stopped 4

Clinical Recommendation Algorithm

1. If having skin prick testing: Stop antihistamines for the appropriate duration (3-10 days depending on medication), but continue montelukast, inhaled corticosteroids, and most other medications 1, 4

2. If having serum IgE blood testing: No need to stop any medications including antihistamines or montelukast 1, 3

3. Always inform your allergist: About all medications you're taking so they can adjust the testing protocol if needed 1

The negative predictive value of skin testing exceeds 95%, while the positive predictive value is less than 50%, meaning false positives are more common than false negatives when medications are properly discontinued 1.