Allergy Testing

In the United States, allergies are among the most common medical conditions, with the American Academy of Asthma Allergy & Immunology reporting that nearly 8% of Americans have hay fever. Approximately 11% of adults and 8% of children and adolescents have food allergies. Not only do allergies cause troubling symptoms, but they also have economic consequences. The Asthma & Allergy Foundation reports that food allergies cost approximately $25 billion per year, while general allergies cost another $18 billion.

This guide provides an overview of the allergy testing process and explains why testing is necessary. It also includes information on common symptoms and treatment options for seasonal allergies and allergies to specific foods.

The purpose of allergy testing is to determine if an individual’s allergy symptoms are caused by a specific substance. Allergy testing helps properly diagnose reactions to mold, pollen, pet dander, dust mites, foods, and other substances, making it easier for people with allergies to manage their symptoms.

A few days of sniffling and sneezing per year aren’t usually anything to worry about, but prolonged symptoms require a visit to an allergist to start the testing process. The American College of Allergy, Asthma & Immunology recommends getting tested under the following conditions:

• Allergy symptoms are causing difficulty breathing, chronic sinus infections, or other complications.
• Over-the-counter medications are no longer effective for controlling allergy symptoms.
• Allergy symptoms last for several months.
• Allergy symptoms are making it difficult to perform normal activities, interfering with the ability to work or go to school, or reducing a person’s overall quality of life.

It’s also important to get tested if allergy symptoms trigger any warning signs of asthma. Wheezing, coughing, struggling to breathe, chest tightness, and shortness of breath are all signs that allergy symptoms may be triggering asthma, a medical condition that can be life-threatening if not treated properly.

Allergy testing may take the form of a skin test or blood test. During a skin test, a trained medical professional puts a drop of each suspected allergen on the skin. The person being tested must remain at the testing site long enough to determine if any of the allergens have caused a reaction. Blood testing requires the individual to provide a blood sample to be analyzed in a laboratory.

No special preparation is required for the blood test. Anyone who plans to undergo skin testing should stop taking antihistamines — a type of over-the-counter allergy medication — for three to seven days before the test occurs.

Seasonal allergies are allergic reactions that cause symptoms at a certain time each year. Many people have allergy symptoms in the spring and summer, but seasonal allergies also occur during the fall and winter. Changes in the temperature, humidity level, and amount of rainfall a region receives can all increase or decrease the amount of an allergen in the environment. For example, mold thrives in moist conditions, causing mold allergies to worsen when humidity levels are high. Wind is another important factor in determining the severity of a person’s seasonal allergy symptoms, as it spreads pollen and other allergens.

Many allergens come from trees, plants, flowers, and grasses. These are some of the most common triggers for seasonal allergy symptoms:

• Mold
• Mildew
• Ragweed pollen
• Pigweed
• Mugwort
• Sagebrush
• Burning bush
• Tumbleweed
• Cocklebur
• Russian thistle

Seasonal allergy symptoms typically affect the nose, mouth, eyes, throat, and skin. Common symptoms include sneezing, coughing, runny nose, nasal congestion, sore throat, watery eyes, and difficulty smelling. If an allergen comes into contact with the skin, the allergic reaction is likely to cause itching, redness, and even hives. Some people with seasonal allergies also experience headaches, a feeling of pressure in the cheeks, and popping of the ears. These symptoms occur due to changes in nasal and sinus pressure.

An allergic reaction to food occurs when an individual ingests a substance that triggers the immune response. The immune system sees the food as a harmful substance instead of something harmless, producing a variety of symptoms. In the United States, a group of eight foods known as the Big-8 is responsible for approximately 90% of all food allergies. This group of foods includes peanuts, tree nuts, wheat, eggs, milk, fish, soy, and shellfish.

Symptoms of a food allergy can range from mild to severe. Mild cases may cause nausea or itching of the mouth. Severe food allergies may cause anaphylaxis, a life-threatening reaction characterized by wheezing, constriction of the airways, rapid pulse, low blood pressure, and other serious symptoms. The following symptoms may also occur as the result of a food allergy:

• Stomach cramps
• Vomiting
• Diarrhea
• Wheezing
• Coughing
• Shortness of breath
• Difficulty swallowing
• Hoarse throat
• Pale skin
• Swelling of the tongue or lips
• Fainting
• Dizziness

During a skin test, a medical professional applies diluted allergens directly to the skin. Many allergens are tested at one time, which helps determine if the individual is allergic to multiple substances. The allergens are applied to the skin with the prick of a needle, but the test shouldn’t cause any pain. Before performing skin testing, a medical professional must evaluate each patient to determine if skin testing is safe and appropriate under the circumstances.

Once the allergens are applied to the skin, the medical professional observes the individual for about 15 minutes to determine if any of the potential allergens are causing a reaction. A skin reaction is characterized by redness and itchy, red bumps at the application site. This is known as a wheal. Severe reactions produce larger wheals than mild reactions.

It’s important for a trained medical professional to conduct a skin test, as it’s possible for the results to be misinterpreted if they’re reviewed by someone without extensive experience conducting allergy tests. It’s also possible for allergies to be misdiagnosed or managed incorrectly if the testing isn’t performed under the supervision of an experienced professional.

Blood testing identifies antibodies to specific foods and other allergens in the blood. Antibodies are proteins produced by the immune system when it detects a potential threat to the human body. The presence of antibodies to a specific food indicates that the immune system sees the food as a threat and responds accordingly any time the individual consumes it. An individual may also have antibodies for pet dander, dust mites, and other allergens. This type of allergy test is performed on a sample of blood taken from one of the veins.

People usually go to a doctor’s office or laboratory to have their blood drawn, but several companies make home testing kits for added convenience. For example, Everlywell offers the indoor and outdoor allergy test, which checks for antibodies to two types of dust mites, two types of pet allergens, two insects, four molds, seven grasses, nine weeds, and 14 trees. The kit contains a collection device that makes it easy to collect a blood sample from a fingertip.

Once the sample is mailed back to the laboratory, the results are reviewed by an independent physician and then delivered via a secure online platform. Although using a home testing kit is more convenient than visiting a laboratory, it’s still important to discuss the results with a qualified medical professional who can develop an appropriate treatment plan.

In some cases, it’s possible to manage the symptoms of seasonal allergies by making some lifestyle changes. For allergies to pollen, mold, mildew, and other outdoor allergens, wearing a mask when working outdoors, keeping the doors and windows closed, and washing outdoor clothing immediately after coming inside can all help limit symptoms. It’s also important to keep an eye on the pollen count and avoid going outdoors when pollen levels are at their highest. If lifestyle changes aren’t enough to get seasonal allergies under control, it may be necessary to take antihistamines, corticosteroids, or decongestants to reduce the symptoms.

• Antihistamines block the release of histamine, a substance produced by the immune system when it identifies an allergen.
• Corticosteroids reduce inflammation, making them useful for dealing with a stuffy nose and other allergy symptoms.
• Decongestants constrict the blood vessels, making them highly effective for treating the congestion caused by seasonal allergies.

Immunotherapy (allergy shots) may also be helpful for preventing allergies. Immunotherapy involves giving an individual gradually increasing doses of an allergen, which makes the immune system less sensitive and may prevent allergic reactions or make them less severe when they occur.

It’s important to talk to a licensed medical professional before taking any allergy medications, as some medications cause serious side effects, especially in people with a history of chronic health conditions.

In most cases, avoiding the allergen is the only way to prevent allergic reactions to foods. Someone who’s allergic to almonds, for example, should be careful to avoid eating whole or chopped almonds, dishes made with almond flour, and other foods that may have been prepared with or come into contact with almonds. In early 2020, the U.S. Food & Drug Administration approved a treatment for peanut allergies in children ages 4 to 17. The treatment, an oral medication called Palforzia, must be taken daily to modify the immune system enough to reduce the risk of an allergic reaction. Palforzia doesn’t cure peanut allergies, but it can reduce their severity.

It depends on which type of test is used. Skin testing results are immediate, as wheals will develop within about 15 minutes if an individual is allergic to any of the allergens that were applied to the skin. Because blood samples have to be analyzed by laboratory professionals, the results of a blood allergy test won’t be ready for several days.

Blood testing has few risks, as it requires just a small sample of blood. Some people feel a little dizzy or faint when having their blood drawn, but the feeling should pass quickly. Skin testing does have some potential risks. During a skin test, the individual is exposed to substances that may cause an allergic reaction. In some people, itching and swelling are the only symptoms. People with severe reactions may start wheezing or have trouble breathing. This is why it’s so important to have the test performed by an experienced medical professional.

Allergies do run in families; however, it’s not possible to predict if a child will have allergies, even if one of the parents is allergic to something. Two parents without allergies can have a child with severe allergies, while two parents with allergies can have a child with no allergy symptoms.

Avoiding allergy triggers is one of the best ways to prevent seasonal allergy symptoms. People who can’t avoid triggers entirely may benefit from doing the following:

• Using a dehumidifier to reduce the indoor humidity level. Mold, mildew, and other allergens thrive in moist conditions, so reducing the humidity level can help prevent their growth.
• Dusting and vacuuming regularly
• Running a HEPA filter to eliminate allergens from the air
• Cleaning up leaks and spills immediately to prevent mold and mildew from growing
• Using a dryer instead of hanging clothes outside to dry. Pollen and other allergens can cling to line-dried clothes.
• Turning on a fan or air conditioner instead of opening the windows to cool down the house

Although some people with food allergies continue to dine at restaurants, it can be difficult to avoid allergens when eating food prepared by someone else. Restaurant staff do their best to accommodate allergies, but cross-contamination can occur. Servers may also be unaware that a potential allergen is in certain dishes. For example, someone allergic to bell peppers obviously can’t have a salad with raw peppers or a pizza with roasted red peppers on top. However, the server may not be aware that the cream sauce used in a pasta dish is flavored with a stock made with bell peppers and other vegetables.

People with severe food allergies should avoid certain establishments to prevent serious allergic reactions. It’s not safe to eat at a buffet, as customers are responsible for serving themselves, which often results in cross-contamination of dishes. Bakeries are unsafe because many items are sold without labels indicating their contents. Baked goods are also made with several of the most common allergens, including eggs and nuts, increasing the risk for cross-contamination.

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