At-Home Allergy Tests are not an alternative for trained clinical allergists
These tests are part of the unregulated wellness industry that sells pseudoscience under the guise of health.
Note: this article appeared originally in my monthly Skeptical Inquirer column, Inside Immunity - I added a few additional details here for more context.
I am publishing it here for another audience, but also to let you know that I will be speaking at this year’s CSICon next month, specifically on the selective rejection of science, a topic I speak on often.
At-Home allergy tests are part of the unregulated wellness industry.
The at-home DIY health industry is booming. The global wellness product market was valued at $5.6 trillion in 2022 and is expected to grow to over $7 trillion by 2025. This includes dietary supplements, nutrition products, fitness equipment, health and wellness apps, and even unapproved consumer health tests.
This market has exploded because of many factors, such as increased attention on overall health and well-being, lack of regulation on wellness products, aggressive marketing efforts by companies including paid promotion by celebrities and online influencers, and a coordinated effort to erode trust in evidence-based medicine.
The immune system is a frequent target; everywhere you turn, there is a product advertising to “boost” your immune system, support immune health, diagnose foods you’re “sensitive” to, and more. Many legitimate scientific terms are co-opted by influencers in the wellness world to sell people on medical issues and products that are not based in reality, which only adds to the confusion among the public. Of course, the appeal is obvious: the immune system is the most complex organ system in the body and is involved in nearly every physiological process from infectious diseases, cancer, autoimmunity, allergies, and even things such as obesity and menstrual cycles. If you could control your immune system, you could truly hack your health.
If only it were that simple.
The reality is there is no evidence that these products are doing what they promise to do. Aside from the fact that these products are a waste of money, many can be seriously harmful. Supplements can be adulterated and contaminated, health tests can cause people to make serious changes to their lifestyle and habits, leading to malnutrition, disordered eating, and worse.
There has also been an increased demand for at-home allergy testing. Before we get into it, I want to say unequivocally that at-home allergy tests should never be used for diagnosis. They are not FDA-approved or validated for use. Their methods and results are not accurate and trusting them can lead to harmful consequences.
Allergies occur when your immune system reacts to substances that your body would normally ignore.
These reactions lead to the symptoms we associated with allergies, as a response to contact with allergens. These allergens are usually protein or sugar components of substances you inhale, touch, or eat. Common sources of allergies include dust mites, pollen, pet dander, peanuts, eggs, milk, and sesame.
When you encounter these substances, your immune system mounts a defense against these substances, producing a specific type of antibodies: immunoglobulin E (IgE). These IgE antibodies tag specific immune cells like mast cells so the next time you are exposed, those mast cells secrete chemicals such as histamine, which lead to symptoms of allergies (swelling, itching, rash, runny nose, watery eyes, etc.). Symptoms can range from sneezing to potentially life-threatening anaphylaxis.
Allergic reactions are elicited in two phases:
Phase 1, the sensitization phase, occurs when your immune system initially flags the substance as foreign and is generally asymptomatic, since your body hasn’t developed the memory immune response yet. This occurs during the first encounter with the allergen (an antigen that is associated with an allergic response). During that process, B cells produce IgE antibodies specific to different regions of the allergen, similar to how we produce antibodies against epitopes of pathogen antigens (discussed here).
These IgE antibodies are secreted by B cells and bind to the outside of mast cells, FcεRI (high affinity IgE receptor). They hang onto those mast cells until the second phase, called elicitation.
Phase 2, elicitation, occurs upon the second exposure to the antigen.
In this phase, those antigens are grabbed by those specific IgE antibodies already hanging onto the mast cells, and when they bind, it triggers activation of mast cells. Mast cell activation leads to degranulation and secretion of a lot of inflammatory chemicals, the most widely known being histamine. These chemicals mediate the symptoms of allergies, which can vary depending on the allergen and the route of exposure (more on that in a more immunology-focused piece, promise!)
The only credible way to diagnose allergies is through the work of a clinical allergist/immunologist.
If you suspect you might have allergies, you’ll want to go to a clinical allergist/immunologist for evaluation and testing. Allergists are physicians with at least two years of residency in allergies and asthma, and they will factor in your medical history, physical exam, and possible allergy testing methods to determine if you truly are allergic to something.
Different allergens bother different people, so an allergist will determine which test is the best for you after collecting a thorough medical history and conducting a physical examination to determine if allergy testing is warranted.
IgE Skin Prick Tests are the most common test used initially. A small amount of a suspected allergen is placed on your skin, usually on the forearm, upper arm, or back. The skin is slightly punctured to introduce the allergen under the surface of the skin, and you’re observed for 15–20 minutes to see if signs of an allergic reaction appear (usually a raised bump, called a wheal, or redness).
Intradermal Skin Tests are similar to a skin prick test, but the substance is injected between the layers of the skin with a needle. This test is often more sensitive and can be used to detect allergies to insect venom or medications such as penicillin.
Patch Tests are used to identify substances causing contact dermatitis, skin allergic reactions from direct contact with substances. This is useful to identify allergies to components in latex, medications, fragrances, preservatives, hair dyes, metals, and resins. Allergens are applied to patches placed on your skin, which will remain there for forty-eight hours to assess if you develop a skin reaction.
Challenge Tests are used for food or oral medication allergies: a very small amount of an allergen is inhaled or taken by mouth under medical supervision. This type of testing must be performed in a clinic with medical interventions on hand, because these types of allergies are those more commonly associated with serious allergic reactions such as anaphylaxis.
IgE Blood Tests might be used if you have a condition that prevents skin testing, such as a skin condition that might interfere with testing. These tests are not as sensitive or specific, which means you can get false positives and false negatives. That’s why you need the interpretation by a trained professional in the context of your medical history to appropriately draw conclusions.
When Might an Allergist Suggest Allergy Testing?
In the context of your medical history and exam, there are going to be symptoms that might raise a flag there might be an allergic condition.
These often include respiratory symptoms such as itchy eyes, nose, or throat; chest congestion; wheezing; coughing; and rhinitis (running nose/sneezing). They might also include severe reactions to stinging insects, beyond swelling at the site of the sting, or severe reactions to consuming foods, including hives, itching, swelling, respiratory issues, gastrointestinal issues (nausea, vomiting, cramping, and diarrhea), and skin rashes consistent with eczema.
The good news? If an allergen is identified, it means you can address those possible exposures.
If it is a food allergen, such as a protein in peanuts, eggs, or dairy, you might need to avoid those foods. If you have pollen-related allergies, you might need to wear a mask or limit time outside when pollen counts are high. There are also medications such as antihistamines that can help moderate your immune response and symptom severity. In some instances, you can undergo treatment to train your immune system to tolerate those substances, called allergy immunotherapy.
But it’s always critical that a trained expert is involved in this to ensure you are using scientifically supported methods and don’t make false interpretations. For example, if you are developing symptoms in your house and have pets, you could have allergies to several things. Some people might assume it is pet dander, but exploration with an allergist may reveal it is actually dust mites. Accurate diagnosis will improve quality of life.
These allergy testing methods described above use FDA-approved methods.
At-home or direct-to-consumer tests claiming to diagnose allergies do not meet those criteria.
But herein lies the confusion. People might think, well hey, my allergist is doing this blood test for IgE, and there’s a company that offers a blood test for IgG that I can do at my house; that’s basically the same thing, right?
Unfortunately, that answer Is no.
A common misconception is that FDA-approved tests and at-home tests (some of which are laboratory-developed tests), even if they claim to test for the same thing, are interchangeable. It underscores a lack of understanding of the steps involved in getting a diagnostic test reviewed, evaluated, and approved for use.
Tests that are FDA-approved for use in clinical diagnostic settings have every single detail studied, critiqued, and analyzed. That means every single chemical; every single step in the process and all the controls and reference materials that you’d use to compare your test results to are all rigorously controlled. But beyond that, every step in the development of the test, every step in the manufacture of the test, all the equipment used to analyze the test samples, even how a lab technician would run the test: all these things are also regulated.
Tests that are not FDA-approved have none of this oversight.
That means there is no quality control on any of this. They can’t verify that the chemicals they’re using are pure, that the levels of a given allergen are even what they say they are, that their control values are accurate, or that they’re using the right materials.
You should never use tests that claim to diagnose allergies that are not approved by the FDA or supported by credible allergy expert organizations.
These include any screening tests done in a grocery store or pharmacy, any at-home testing, allergy testing by testing muscle strength or weakness, cytotoxicity testing for food allergy, Rinkel skin titration method, provocative neutralization testing, and Immunoglobulin G (IgG) testing for food “sensitivity.” These are not accurate, are ineffective, and can lead to false diagnoses and treatments.
Two that are growing in population are finger prick testing and urine testing: neither are accurate ways to diagnose allergies.
Finger prick allergy tests typically involve collecting a small blood sample from a finger prick, which is then sent to a laboratory for analysis. The lab checks for the presence of specific Immunoglobulin E (IgE) antibodies to various allergens. While many people may think this is similar to an IgE blood test administered by an allergist, that’s not the case.
The quality and quantity of blood obtained from a finger prick is not adequate for accurate testing. Blood from a fingertip extremity is not the same as venous blood that would be collected for clinical IgE testing. Moreover, individuals are not trained in proper sample collection methods when self-administering these at-home tests.
The labs these tests use for testing do not have the same quality standards as the FDA-approved methods detailed above so the results they report are unreliable. At-home allergy tests are not regulated or approved by medical regulatory bodies.
Even if these tests identify specific IgE antibodies, interpreting what these findings mean without expert clinical training is not feasible. Remember, even the IgE blood tests have issues with sensitivity and specificity, meaning they can give you false positive and false negative results. Just because you may have IgE presence in a blood sample doesn’t mean you automatically have a clinical allergy.
A positive test result doesn’t always mean you’ll experience allergic reactions. That is why any testing must be interpreted by an expert alongside an exam and medical history, to avoid misinterpretation of results that could lead to unnecessary dietary or lifestyle restrictions.
Urine tests are not a standard or scientifically validated method for diagnosing allergies. The concept of using urine tests for allergy diagnosis is based on an assumption that certain substances, such as IgE antibodies, might be present in the urine of individuals with allergies.
The issue with these is more obvious: there’s no scientific evidence to support this rationale for urine testing for allergies.
Standard allergy tests, such as skin and blood tests, have been extensively studied and validated. Urine is a waste product excreted by your body, and urine components are influenced by countless factors including diet, hydration, kidney function, and medications. You can’t relate changes in urine composition to an allergic reaction, the same way you can’t relate changes in urine composition to “exposure” to harmful substances. Urine removes things from your body that you don’t need.
There is no relationship between urine levels of IgE antibodies and allergies. Just because something is found in a waste product such as urine does not mean it has clinical relevance. (This is the same tactic used when people fearmonger about trace pesticide residues found in urine, or phthalates, or similar. Finding something in urine means your body is removing it.)
Relying on unvalidated testing methods such as urine tests or finger prick tests for allergies can lead to misdiagnosis, inappropriate treatment, and potentially overlooking other underlying health issues. While these may seem like convenient methods, they are not a replacement for professional expert evaluation and FDA-approved testing.
Unfortunately, there’s a growing faction of outspoken individuals, even those with apparent science or medical training, that are actively working to try to instill distrust in credible science and evidence-based medicine.
It’s advertised under the guise of empowering you to take control of your health. But these interventions being sold to you are only misleading you, costing money, and causing harm. Please be wary.
Thank you for supporting evidence-based science communication. With outbreaks of preventable diseases, refusal of evidence-based medical interventions, propagation of pseudoscience by prominent public “personalities”, it’s needed now more than ever.
Stay skeptical,
Andrea
“ImmunoLogic” is written by Dr. Andrea Love, PhD - immunologist and microbiologist. She works full-time in life sciences biotech and has had a lifelong passion for closing the science literacy gap and combating pseudoscience and health misinformation as far back as her childhood. This newsletter and her science communication on her social media pages are born from that passion. Follow on Instagram, Threads, Twitter, and Facebook, or support the newsletter by subscribing below:
Thank you for this thorough explanation.