Allergic Patients With Negative Allergy Test Results
by Dr. Christopher Chang, last modified on
Occasionally, there are patients with histories and symptoms all consistent with allergies (environmental as well as foods)... BUT, when tested for allergies, everything comes back negative whether by skin or blood testing. This scenario is a tricky situation for which there is no easy answer, especially for those patients who desire to be treated with allergy shots/drops.
What may be happening here? Well, let's start by asking the question,
"Is it possible to have allergies even if the allergy testing comes back negative?"
The answer is absolutely yes! But how can that be?!! Well, here is the simplified answer. When allergy testing is performed whether by skin prick or blood testing (RAST or immunoCAP), one is testing to certain specific proteins known to cause allergic reactions in majority but not all patients (these are called major allergen). Patients need to remember that for a given allergy like CAT... there are millions of proteins (minor allergen) that have the potential to cause an allergic reaction. Allergy testing to cat ONLY tests for ONE of these proteins called Fel d1 as well as a few other minor allergens. As such, if a patient is CAT allergic but not to the Fel d1 protein, then the allergy testing will come back normal!
Given this information, that's why skin testing is a bit more "accurate" when it comes to determining whether a patient has allergies or not as there are more "proteins" for a given allergen like CAT being tested than the blood test like RAST/immunoCAP which STRICTLY tests for a single protein.
Click here to read more about this.
OK... So what can be done for allergic patients with negative test results?
Usually, patients are told to continue with allergy medications (antihistamines, steroid nasal sprays, etc) as there are no other options. However, in our practice we do provide other options for treatment including multi-antigen allergy drops. One is a candidate for this option if the total serum IgE level is >200 IU/ml with a good history strongly suggestive of environmental allergies.
What if a patient truly has no allergies?
Are you using a nasal decongestant spray regularly on a daily basis like Afrin? If so, you may be suffering from rhinitis medicamentosa, otherwise known as afrin addiction. Read here to learn more about this condition and how it is treated.
The other possibility is that you may have vasomotor rhinnitis (also known as non-allergic rhinitis) and not allergies. Vasomotor rhinnitis causes many of the same sort of symptoms as allergies, but is due to pollen and other "allergic" substances acting more as physical irritants rather than an immune response which is what allergies are caused by. If that is the case, medications such as patanse, astelin, and atrovent nasal sprays work the best along with saline flushes (video). Ponaris as well as Sinus Plumber (which uses capsaicin) have also been found to be helpful.
Another possiblity in up to 40% of patients with normal allergy test results is a condition called "Local Allergic Rhinitis." Read more about this condition here.
A final possibility is "histamine intolerance." This condition is mainly found in middle-aged women who develop symptoms after eating histamine-rich foods such as alcohol, processed meats, fermented foods, cheese, etc. Treatment is by following a histamine-free diet +/- antihistamine use.
Please note that we do NOT treat patients with severe symptomatic asthma (patients who use inhalers daily). We are an ENT allergy practice and as such, deal only with problems above the shoulders which excludes the lungs and asthma.
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