Understanding Montelukast and Its Role
Montelukast, widely known by its brand name Singulair, is a prescription medication used to manage asthma and allergic rhinitis (hay fever). It belongs to a class of drugs called leukotriene receptor antagonists. Its primary function is to block the action of leukotrienes, which are inflammatory chemicals the body releases during an allergic reaction. These chemicals cause swelling in your nasal passages, increased mucus production, and tightening of the airways. By inhibiting leukotrienes, montelukast helps to control these symptoms.
How Does Allergy Skin Testing Work?
Allergy skin testing, often done via a skin prick test, is a primary diagnostic tool to identify allergens. The test involves placing a small amount of a suspected allergen onto the skin and then lightly pricking the area. If you are allergic, your immune system releases histamine, causing a localized reaction that looks like a small mosquito bite, known as a wheal and flare. The size of this reaction helps the allergist determine your sensitivity to that specific allergen. For this test to be accurate, the body's histamine response must not be suppressed.
The Verdict: Montelukast and Allergy Test Accuracy
The core reason certain medications must be stopped before allergy testing is their potential to interfere with the histamine-driven wheal and flare reaction. Antihistamines, as their name suggests, directly block histamine receptors, which would prevent the skin from reacting to an allergen and lead to a false-negative result.
However, montelukast works on a different pathway. It targets leukotrienes, not histamine. Multiple studies and clinical guidelines confirm that leukotriene modifiers like montelukast do not significantly suppress the skin's reaction during a skin prick test. Therefore, medical authorities like UCSF Health, Dartmouth-Hitchcock, and others state that patients can and should continue taking montelukast as prescribed before their allergy test. This allows patients to maintain control over their asthma or allergy symptoms while still getting accurate diagnostic results.
Which Medications DO Interfere with Allergy Testing?
While montelukast is generally safe to continue, many other common medications must be stopped. The washout period (how long before the test you must stop) varies by drug. Always confirm with your prescribing doctor before stopping any medication.
- Antihistamines: This is the most critical group to avoid. This includes first-generation (like diphenhydramine/Benadryl) and second-generation (like cetirizine/Zyrtec, loratadine/Claritin, fexofenadine/Allegra) oral antihistamines. They typically need to be stopped 3 to 7 days before testing.
- Antihistamine Nasal Sprays and Eye Drops: Products like azelastine (Astelin, Astepro) or olopatadine (Patanase) also need to be discontinued, usually for a few days prior to the test.
- Certain Antidepressants: Tricyclic antidepressants, such as amitriptyline and doxepin, have strong antihistamine properties and can interfere with results. The washout period can be a week or more, and you must consult the prescribing physician before stopping them.
- H2 Blockers: Some medications used for acid reflux, like famotidine (Pepcid) and cimetidine (Tagamet), are H2 antihistamines and should be stopped at least a day or two before the test.
- Other Medications: Over-the-counter cold and sleep aids often contain antihistamines (e.g., Tylenol PM, Nyquil), so it's crucial to read labels carefully.
Comparison Table: Medications and Allergy Skin Test Interference
| Medication Class | Example(s) | Interferes with Test? | General Guideline |
|---|---|---|---|
| Leukotriene Modifiers | Montelukast (Singulair), Zafirlukast | No | Continue taking as prescribed. |
| Inhaled/Nasal Steroids | Fluticasone (Flonase), Budesonide | No | Continue taking as prescribed. |
| Oral/Inhaled Bronchodilators | Albuterol (Ventolin), Salmeterol | No | Continue taking as prescribed. |
| 2nd-Gen Antihistamines | Cetirizine (Zyrtec), Loratadine (Claritin) | Yes | Stop 5-7 days prior. |
| 1st-Gen Antihistamines | Diphenhydramine (Benadryl) | Yes | Stop 3-5 days prior. |
| Tricyclic Antidepressants | Amitriptyline, Doxepin | Yes | Stop 7+ days prior, with doctor approval only. |
| H2 Blockers | Famotidine (Pepcid), Cimetidine (Tagamet) | Yes | Stop 1-2 days prior. |
Preparing for Your Allergy Test
To ensure the most accurate results, follow these general steps, but always prioritize the specific instructions from your allergist's office.
- Review Your Medications: Provide your doctor with a complete list of all prescription drugs, over-the-counter medicines, and supplements you take. They will give you a specific list of what to stop and when.
- Don't Stop Prescriptions Abruptly: Never discontinue medications for chronic conditions like depression, high blood pressure, or heart disease without explicit approval from your prescribing physician.
- Avoid Topical Creams: Do not apply lotions, creams, or topical steroids to the testing area (usually the back or arms) on the day of your appointment.
- Dress Comfortably: Wear loose-fitting clothing, ideally with short sleeves, to allow easy access to your arms.
Conclusion
For individuals managing allergies and asthma, the evidence is clear: you can safely continue taking montelukast before an allergy test. Its mechanism of action does not interfere with the histamine response that skin tests rely on, unlike antihistamines which must be stopped several days in advance. Communication is key; always discuss your full medication regimen with your allergist to receive personalized instructions and ensure your test results are accurate and reliable. For more information, the American Academy of Otolaryngic Allergy offers helpful resources.
