Food allergies are on the rise, affecting more children and adults than ever before. It is vital to identify offending food sources, as they negatively affect our quality of life and even pose significant health risks.

This article explains what food allergy testing looks like and what risks and results to expect from different types of tests.

What Is a Food Allergy Test?

Food allergy testing is used to determine whether a person is allergic to a specific food. It also helps to distinguish between a food allergy (an immune reaction) and a food intolerance, which may produce similar but less dangerous symptoms.

Types of Food Allergy Tests

The doctor may use multiple food allergy tests to diagnose the condition and prescribe the appropriate treatment. Each type has its strengths and limitations. Combining different testing methods increases accuracy and efficacy.

Below we describe the different food allergy tests and how they work.

‌Skin Prick Testing (SPT)

Skin prick testing (SPT) is the fastest, most common, and cost-effective method for detecting food allergies. It helps diagnose immediate allergic reactions to foods and airborne allergens (e.g., pollen, animal dander, and mites).

The nurse will prick the skin on your forearm or back using a fine needle or scratch the skin using a sterile scalpel. They will expose the scratched area to all suspected allergens in liquid form. SPT can detect up to fifty allergens at once.

If a reaction occurs, your skin will break out in a rash or wheals (inflamed raised spots).

SPT covers a broad range of food allergens, including the following:

• Meat - Chicken, beef, pork, mutton, and duck.
• Fish – Cod, carp, tuna, scallops, catfish, shrimp, mussels, and spiny lobster.
• Eggs and dairy – Cow’s milk, whole egg, egg white, and egg yolk.
• Vegetables – Potato, parsley, spinach, cabbage, soybean, leek, tomato, and spring onion.
• Fruit – Apple, orange, banana, peach, tangerine, pineapple, grapes, strawberries, and mango.
• Nuts and seeds – Almonds, cashew nuts, walnuts, sunflower seeds, pine nuts, cocoa beans, pumpkin seeds, hazelnuts, chestnuts, macadamia nuts, Brazil nuts, and pistachio.
• Flours – Corn, wheat, rice, buckwheat, and green bean.
• Spices – Cocoa, cinnamon, black pepper, paprika, sesame, and garlic.

Atopy Patch Testing (APT)

Atopy patch testing (APT) is a diagnostic tool used to detect aeroallergens and allergenic foods that cause eczema (e.g., atopic dermatitis or contact dermatitis). It is indicated in cases of persistent atopic dermatitis with unknown triggers or when skin prick tests are negative.

APT involves placing a few drops of allergens onto your arm or back and covering it with a small patch-like bandage for two to four days. The doctor will remove the patches after 24-72 hours to examine the skin’s condition and look for any eczematous skin lesions, flare-ups, or rashes.

The most common food allergens assessed through APT include:

• Cow’s milk
• Hen’s eggs
• Wheat
• Soy products

Allergy Blood Test

An allergy blood test, also known as an allergen-specific immunoglobulin E (IgE), measures the presence of immunoglobulin E (IgE) in the blood. By measuring levels of IgE antibodies to specific foods, this test helps to identify and better manage different food allergies.

The procedure involves drawing a small blood sample from the vein and sending it to a laboratory to be mixed with potential allergens. The level of IgE antibodies is then checked to determine a food-specific allergic reaction.

Unlike the skin prick test, an allergy blood test is not affected by antihistamines, making it a preferable option for patients with extensive rashes.

Oral Food Challenge (OFC)

Oral food challenge (OFC) is the “gold standard” for diagnosing food allergies and is considered the most accurate and reliable testing method. It consists of ingesting small amounts of potential allergens and monitoring the body for reactions.

Only one food allergen is tested at a time, and the dosage is gradually increased as the allergist closely observes the patient’s body for symptoms such as bloating, rashes, or breathing difficulties. If no reaction occurs after you have had the entire dose, the test results are negative.

This test is only performed under strict medical supervision in a medical facility due to the high risk of severe allergic reactions, such as anaphylaxis.

A Food Elimination Diet

This diagnostic approach involves removing suspected food allergens from your diet for two to four weeks. Elimination diets help identify specific foods or ingredients that may cause allergic reactions. They can also confirm the results of skin prick tests or blood tests.

The foods may be later reintroduced one at a time. This method’s biggest disadvantage is that it does not distinguish between a food allergy and an intolerance or sensitivity.

If you decide to do an elimination diet, consult a registered dietitian to avoid potential nutrient deficiencies and seek a professional healthcare provider for guidelines tailored to your needs.

Component-Resolved Diagnostics (CRD)

Component-resolved diagnostics (CRD), known as molecular allergy testing, is an advanced diagnostic method that provides a detailed analysis of food allergies. It involves drawing a blood sample to pinpoint specific proteins (components) within an allergen that cause an immune response.

CRD aims to distinguish between true food allergies and cross-reactivity with other allergens on a molecular level. This type of test is beneficial for individuals who avoid eating all nuts due to a suspected reaction to one nut.

Basophil Activation Test (BAT)

Basophil activation test (BAT) is a sophisticated diagnostic procedure performed on a type of white blood cells called basophils. Studies highlight its efficacy and non-invasiveness in contrast to other testing methods.

This test helps to identify cross-reactive allergens and confirm food allergies, especially when other results are inconclusive or conflicting. However, scientific research for BAT is still limited and requires more clinical validation.

Who Should Take a Food Allergy Test?

People of all ages who experience unpleasant symptoms after eating certain foods can take a food allergy test. While most food allergies develop in early childhood, they can also occur and persist in adulthood.

People with chronic autoimmune illnesses or a family history of allergies and anaphylaxis are at risk for developing food allergies and should take extra precautions.

This test can also benefit individuals with health conditions that are triggered or worsened by food, such as the following:

• Eczema
• Acne
• Rosacea
• Atopic dermatitis
• Asthma
• Irritable bowel syndrome (IBS)
• Inflammatory bowel disease (IBD)
• Celiac disease
• Rheumatoid arthritis
• Gastroesophageal reflux disease (GERD)

How to Prepare for a Food Allergy Test?

To prepare for the test and ensure reliable results, you should follow these instructions:

• Stop taking medication and supplements before the test, as your doctor advises.
• Avoid prescribed or over-the-counter antihistamines (e.g., Allegra, Claritin, Xyzal, Benadryl, Tagamet, Pepcid, and Zantac), including nasal antihistamine sprays (e.g., Azelastine or Olopatadine)
• Avoid medication with antihistamine-like activity, such as tricyclic antidepressants (TCAs).
• Avoid beta-blockers, such as Metoprolol or Timolol.
• Do not wear cologne, hair spray, or scented body lotion.
• Follow specific instructions your doctor provides, such as fasting or avoiding certain foods.
• Wear comfortable, loose-fitting clothes to avoid skin irritation.
• Bring necessary documentation, such as your medical record, food intake diary, or past test results.

You will need the doctor’s permission to discontinue any medication. Do not alter your dosages without consulting the doctor or the allergist.

What Happens During a Food Allergy Test?

‌Prior to the testing, the doctor will discuss the patient’s suspected food allergies, symptoms, family health history, and medical record. A physical examination is performed right before the test to determine the severity of the condition.

• Skin testing - A small amount of allergen is placed on the skin’s forearm or back. The skin is lightly pricked or scratched to allow the allergen to enter and cause a reaction, typically a raised bump. The test typically takes twenty to forty minutes.
• Patch testing - Small amounts of allergens are applied to patches and placed on the patient’s skin. The patches are typically removed after 24 or 48 hours.
• Blood testing - The procedure consists of drawing a blood sample from a vein, typically in your arm, using a needle and a vial or a test tube. The sample is then sent to a lab to measure immunoglobulin E (IgE) antibody levels.
• Oral food challenge - The allergist feeds the patient with suspected food allergens, gradually increasing the amount and closely observing for any signs of reactions. The challenge stops with the first signs (e.g., hives). Medication may be given to relieve the symptoms if necessary.

Depending on the type of test, the provider may apply a numbing cream to minimize discomfort from the antigens, such as itching or tenderness.

The Results of a Food Allergy Test

Results vary depending on the patient’s age, severity of allergy, allergen concentration and stability, and the type of allergy test.

• Skin test - Delivers immediate results visible as bumps, welts, or inflamed patches on the skin’s surface.
• Patch test - Preliminaryresultsarrive 24 to 48 hours after the application. After a few days, the skin may be rechecked for delayed reactions.
• Oral food challenge - Delivers results within a few hours (e.g., hives, swelling, bloating). This type of test is the only one that can confirm a diagnosis of a food allergy.
• Food elimination program - Takes days or weeks to complete.
• Blood testing – The results show higher-than-normal levels of IgE antibodies, and may take a few days to arrive.

‌If you test positive, the doctor will discuss food elimination strategies and preventive measures if you accidentally ingest the offending food. Doctors may also recommend combining different types of allergy tests to better identify foods causing allergic symptoms as undigested food proteins or proteins that are structurally similar (e.g., different members of the legume family) may cause false positive results.

What Preventive Measures Can You Take?

There is no cure for food allergies, but your doctor may recommend some of the following preventive measures based on the severity of your symptoms:

• Avoid trigger foods while cooking, consuming, or preparing food.
• Use separate utensils and cookware when preparing food.
• Carefully read food labels for potential allergenic ingredients.
• Explain your condition to others.
• Wear a medical alert bracelet that identifies your food allergies.
• In case of a severe or life-threatening reaction (e.g., anaphylaxis), use an autoinjector with epinephrine, an emergency allergy medicine.

Are Food Allergy Tests Dangerous?

Allergy tests are considered safe but are not entirely risk-free. They may trigger some of the following reactions:

• Skin irritation (skin prick test)
• Itchiness (skin prick test)
• Slight pain (blood test)
• Tenderness (blood test)
• Soreness (blood test)
• Bruising at the injection site (blood test)

Most symptoms are temporary and subside quickly. Your allergist may prescribe medications to relieve the symptoms and reduce inflammation.

An oral challenge test and an elimination diet may cause a severe allergic reaction and thus require strict medical supervision.

Note: Learn about skin inflammation and practical ways to alleviate it.

Is a Home Food Allergy Test Reliable?

‌Home test kits are available but not widely recommended for the following reasons:

• They are not reliable indicators of specific food allergies.
• They lack scientific validation and clinical evidence.
• They often lack the sensitivity and specificity of tests performed in a clinical setting.
• Only healthcare providers can accurately interpret the results.
• At-home kits may lead to misdiagnosis and unnecessary dietary restrictions.

Food Allergy Testing Cost

The cost of food allergy testing depends on the type of test and whether the patient's insurance covers it.‌ On average, an allergy skin test ranges from $60 to $300, while an allergy blood test can cost between $200 and $1,000 without insurance.

Vibrant Skin Bar does not test for allergies but offers a comprehensive food intolerance test, which can help you determine your food sensitivities, alter your diet, and achieve your health goals.

Conclusion

Food allergy tests help identify and manage food allergies. They are not fool proof, but you can maximize their accuracy by combining one or two testing methods in consultation with your allergist.

Dietary adjustments, avoidance strategies, and emergency action plans can effectively reduce gastrointestinal sensitivities, inflammation, and swelling symptoms.

Learn more about food sensitivities from our friendly medical staff at Vibrant Vitality Clinic.