Food allergy testing and treatment in Waco, TX

Your child ate a cashew at a birthday party and broke out in hives within minutes. Or you bit into shrimp at a restaurant and felt your throat start to tighten. Or maybe you have been avoiding peanuts your whole life because of a reaction you had as a toddler that your parents described to you, but you have never actually been tested to confirm it. Food allergy is one of the areas where accurate diagnosis matters enormously, because the stakes range from unnecessary dietary restriction on one end to life-threatening anaphylaxis on the other. Getting tested, and getting tested properly, is the first step to managing food allergy safely and living with less anxiety around food.

Key takeaways

• Accurate food allergy diagnosis requires more than a blood test or skin test alone, because positive tests can reflect sensitization without clinical allergy, leading to unnecessary food avoidance
• The nine major food allergens (peanut, tree nuts, milk, egg, wheat, soy, fish, shellfish, sesame) account for approximately 90 percent of all food allergy reactions
• Emergency preparedness, including carrying epinephrine (EpiPen or Neffy) and having an action plan, is the foundation of food allergy management

Food allergy vs. food intolerance: why the distinction matters

A food allergy is an immune-mediated reaction involving IgE antibodies. When you eat a food you are truly allergic to, your immune system recognizes the food protein as a threat and mounts a rapid inflammatory response: histamine release from mast cells, tissue swelling, and potentially anaphylaxis. Reactions typically occur within minutes to two hours of eating the food and can range from hives and vomiting to throat swelling and cardiovascular collapse. Food allergies can be fatal.

Food intolerance is a non-immune digestive problem. Lactose intolerance occurs because you lack the enzyme (lactase) needed to digest milk sugar. Eating dairy causes bloating, gas, cramping, and diarrhea, which is uncomfortable but not dangerous. There is no immune activation, no risk of anaphylaxis, and no need for epinephrine. The same is true of many other food sensitivities: they cause real symptoms, but they operate through digestive mechanisms rather than immune ones.

The distinction matters clinically because a true food allergy requires strict avoidance and emergency preparedness (carrying epinephrine, having an action plan, educating family and school staff). An intolerance can often be managed with dietary adjustments, enzyme supplements, or simply knowing your personal threshold. Mislabeling an intolerance as an allergy creates unnecessary fear, social limitation, and dietary restriction. Mislabeling an allergy as an intolerance can be dangerous if the patient does not take appropriate precautions.

How food allergy testing works

Skin prick testing

Small amounts of food protein extracts are applied to the skin (usually the forearm or back) and a tiny prick device introduces the extract into the outer layer of skin. If you are sensitized to the food, IgE antibodies on mast cells in the skin recognize the protein and trigger local histamine release, producing a raised wheal (similar to a mosquito bite) within 15 to 20 minutes. The size of the wheal is measured and recorded.

Skin prick testing is fast, relatively inexpensive, and provides immediate results. A negative test is very reliable: if the skin does not react, you are extremely unlikely to have an IgE-mediated allergy to that food (negative predictive value greater than 95 percent). This makes skin testing excellent for ruling out food allergies.

A positive test is more complicated. Many people have positive skin tests to foods they eat regularly without any symptoms. This is called sensitization without clinical allergy. Your immune system produces IgE to the food protein, but the level is not sufficient to trigger symptoms when you actually eat the food. Depending on the food, 50 to 80 percent of positive skin tests may not correspond to clinical allergy. This is why positive skin tests should never be used as the sole basis for eliminating foods from the diet. A positive test means "your immune system recognizes this protein." It does not necessarily mean "eating this food will make you sick."

Blood tests (specific IgE)

Blood tests measure the concentration of food-specific IgE antibodies circulating in your bloodstream. Higher levels generally correlate with greater probability of clinical allergy, and research has established probability thresholds for common allergens. For example, a peanut-specific IgE above approximately 14 kU/L predicts a greater than 95 percent probability of clinical reaction in children. These thresholds help allergists estimate the likelihood of true allergy based on lab values.

Blood tests have similar limitations to skin tests: they measure sensitization, not clinical allergy. A positive blood test with a low IgE level may reflect cross-reactivity or clinically irrelevant sensitization. Blood tests are most useful when skin testing cannot be performed (patients unable to stop antihistamines, patients with severe eczema covering the test areas, very young infants), when confirming skin test results, and when tracking IgE levels over time to assess whether a child may be outgrowing an allergy.

Component-resolved diagnostics

This is a newer and more precise form of blood testing that measures IgE to specific individual proteins within a food rather than the whole food extract. Each food contains multiple proteins, and not all of them are equally dangerous. For peanut, component testing can distinguish between IgE to Ara h 2 (a storage protein strongly associated with severe systemic reactions and true peanut allergy) and IgE to Ara h 8 (a PR-10 protein that cross-reacts with birch and oak pollen and is associated with mild oral symptoms, not anaphylaxis).

This distinction has significant clinical implications. A patient with IgE only to Ara h 8 likely has pollen food syndrome to peanut rather than true peanut allergy, and their risk profile is very different from a patient with IgE to Ara h 2. Component testing is particularly valuable for tree nuts (distinguishing cross-reactive from primary allergy), peanut (risk stratification), and milk and egg (predicting likelihood of tolerating baked forms).

Oral food challenges: the gold standard

The oral food challenge (OFC) is the definitive test for confirming or ruling out a food allergy. Under medical supervision in a clinical setting equipped with emergency resuscitation equipment, the patient eats gradually increasing amounts of the suspect food over a period of one to two hours. Doses typically start very small (milligrams) and increase in roughly doubling increments every 15 to 30 minutes until a standard serving size is reached or a reaction occurs.

If the patient completes the full challenge dose without any reaction, they are not allergic to that food, regardless of what their skin test or blood test showed. The challenge definitively overrides test results. This is important for patients who have been avoiding a food for years based on a positive test and want to know if they can safely eat it.

If a reaction occurs at any point during the challenge (hives, vomiting, throat symptoms, breathing difficulty, blood pressure drop), the challenge is stopped and the reaction is treated immediately. The nature and severity of the reaction are documented and guide the management plan going forward.

Oral food challenges are the single most valuable tool for preventing unnecessary food avoidance. We regularly perform challenges for children who were diagnosed with food allergies as infants or toddlers and whose parents want to know if they have outgrown the allergy. We also challenge adults who have been carrying a food allergy label since childhood without recent testing. The relief when a patient passes a challenge and learns they can eat a food they have been avoiding for years is one of the most rewarding things we do in clinic.

The nine major food allergens

Nine foods (as of 2023, when sesame was added) account for approximately 90 percent of all food allergy reactions in the United States. Each has its own clinical profile, natural history, and management considerations.

Peanuts

Peanut allergy is one of the most common and most feared food allergies because of its association with severe anaphylaxis. It affects roughly 2 percent of children in the United States and has been increasing in prevalence. Unlike milk and egg allergies, peanut allergy is less commonly outgrown: only about 20 percent of peanut-allergic children develop tolerance. Peanut is present in many processed foods, sauces, and restaurant preparations, making accidental exposure a constant concern. Early introduction of peanut to infants (around 4 to 6 months, as recommended by the LEAP study findings) has been shown to reduce the risk of developing peanut allergy in high-risk children.

Tree nuts

Tree nut allergy (almonds, cashews, walnuts, pecans, pistachios, macadamia nuts, Brazil nuts, hazelnuts) is often lifelong and carries significant anaphylaxis risk. Some patients are allergic to one specific tree nut. Others react to multiple. Cross-reactivity between tree nuts exists (cashew and pistachio are closely related, as are walnut and pecan), so testing for all tree nuts is recommended when one allergy is confirmed. In Central Texas, pecans are everywhere (it is the state tree), so pecan allergy has particular local relevance for avoiding both the nut itself and pecan-containing foods at restaurants and family gatherings.

Cow's milk

Milk allergy is the most common food allergy in young children, affecting 2 to 3 percent of infants. It is distinct from lactose intolerance. Milk allergy involves immune reactions to milk proteins (casein, whey), while lactose intolerance is an enzyme deficiency affecting milk sugar digestion. The good news is that most children outgrow milk allergy: approximately 80 percent by age 16. Many children develop tolerance to baked milk (in muffins, cookies, bread) before they tolerate unheated milk (drinking milk, cheese, yogurt). Introducing baked milk under allergist guidance can accelerate the tolerance process.

Eggs

Egg allergy is the second most common food allergy in children. Like milk, it is frequently outgrown: about 70 percent of egg-allergic children develop tolerance by school age. Most egg-allergic children tolerate baked egg (in cake, muffins, bread) before tolerating less-heated egg (scrambled, fried). Egg allergy is relevant for vaccine administration, though most modern flu and COVID vaccines contain negligible egg protein and can be safely given to egg-allergic patients under standard protocols.

Wheat

Wheat allergy involves IgE-mediated reactions to wheat proteins. It is distinct from celiac disease (an autoimmune condition triggered by gluten) and non-celiac gluten sensitivity (a poorly defined condition with unclear mechanism). True wheat allergy is more common in children and often outgrown. Reactions can include hives, breathing difficulty, and anaphylaxis. Wheat-dependent exercise-induced anaphylaxis is a specific syndrome where wheat consumption followed by exercise triggers anaphylaxis, while either wheat alone or exercise alone does not.

Soy

Soy allergy is most common in infancy and early childhood and is frequently outgrown. Soy is present in a vast number of processed foods, making strict avoidance challenging. Fortunately, most soy-allergic individuals tolerate highly refined soy products (soy oil, soy lecithin) because the allergenic proteins are removed or denatured during processing. Soy sauce, despite its name, is typically tolerated because the fermentation process breaks down the allergenic proteins.

Fish and shellfish

Shellfish allergy (shrimp, crab, lobster, clam, oyster) is the most common food allergy in adults, affecting approximately 2 percent of the US adult population. Fish allergy (salmon, tuna, cod, halibut) is separate from shellfish allergy because the allergenic proteins are different: parvalbumin in fish, tropomyosin in shellfish. You can be allergic to one and not the other. Both tend to be lifelong. Both can cause severe anaphylaxis. Patients with shellfish allergy do not need to avoid iodine or contrast dye (this is a persistent myth with no immunological basis).

Sesame

Sesame allergy has been increasing in prevalence and was added to US mandatory food labeling requirements in January 2023. Sesame is found in hummus, tahini, many Middle Eastern and Asian dishes, bread products (hamburger buns, bagels), and some crackers and snack foods. Cross-contamination in restaurants is common because sesame oil and seeds are used widely. Sesame allergy can cause severe reactions including anaphylaxis.

Food allergy in children vs. adults

Children are more likely to have allergies to milk, egg, wheat, and soy, many of which are outgrown during childhood. The likelihood of outgrowing depends on the specific food, the severity of the initial reaction, and the IgE level over time. Declining IgE levels on serial blood tests suggest that tolerance may be developing, at which point an oral food challenge can confirm whether the allergy has resolved.

Adults are more likely to develop allergies to shellfish, fish, and tree nuts, which tend to persist lifelong. Some adults develop food allergies for the first time in adulthood, even to foods they previously consumed without problems. Adult-onset food allergy is becoming increasingly recognized and can be just as severe as childhood-onset allergy. Shellfish is the most common adult-onset food allergy.

School allergy action plans

For food-allergic children, a school allergy action plan is an essential medical document. Signed by the allergist, it specifies the child's allergens, lists symptoms to watch for at each severity level, provides medication dosing instructions including when and how to administer epinephrine, identifies whether the child can self-carry and self-administer, and lists emergency contact numbers. We provide these for every food-allergic child in our practice and update them annually or when the allergy profile changes. School is where many accidental exposures occur (shared snacks, birthday treats, cafeteria cross-contamination), and having a clear action plan in place can be the difference between a managed reaction and a medical emergency.

Emergency preparedness

Anyone with a food allergy that has caused or could cause anaphylaxis needs to carry epinephrine at all times. This is not optional. Reactions can be unpredictable in severity: a food that caused only hives last time can cause anaphylaxis the next time, because the immune response can escalate without warning.

Traditional epinephrine auto-injectors (EpiPen, Auvi-Q) are the most widely prescribed form. They are designed for self-administration through clothing into the outer thigh. Each device contains a single dose, and patients should carry two devices in case a second dose is needed (biphasic reactions, where symptoms recur after initial improvement, occur in up to 20 percent of anaphylaxis cases).

Neffy is the first FDA-approved needle-free epinephrine delivery system, administered as a nasal spray. It provides an alternative for patients who are uncomfortable with needles, who have difficulty with the injection technique, or who want a more discreet option. The nasal spray is simple to use: insert into one nostril and press the plunger. We prescribe and train patients on all available epinephrine devices and ensure they are comfortable with the device they carry.

Emerging treatments

Oral immunotherapy (OIT)

Oral immunotherapy involves consuming gradually increasing amounts of the allergenic food under medical supervision, starting from microgram quantities and working up over months to a maintenance dose equivalent to one or more servings. The goal is to raise the reaction threshold so that accidental exposures to small amounts are less likely to cause severe symptoms.

Palforzia is an FDA-approved peanut OIT product for patients aged 4 through 17. It provides a standardized dosing protocol with documented safety and efficacy data. OIT for other foods (milk, egg, tree nuts, sesame) is available through allergist-supervised protocols at specialized centers. The treatment requires daily dosing to maintain protection and does not cure the allergy. It raises the threshold, providing a safety buffer against accidental exposure while strict avoidance remains the primary strategy.

OIT is not without risks. Allergic reactions during the dose escalation phase are common, and a small percentage of patients develop eosinophilic esophagitis during treatment. The decision to pursue OIT involves balancing the benefit of increased protection against accidental exposure with the burden and risks of daily dosing and the ongoing commitment required to maintain tolerance.

Getting tested

If you suspect a food allergy in yourself or your child, proper testing provides the clarity you need to manage it safely. If you have been carrying a food allergy label since childhood and have never been retested, you may have outgrown the allergy, and an evaluation can determine whether continued avoidance is necessary. If you have been avoiding foods based on a positive blood test without clinical correlation, you may be restricting your diet unnecessarily.

Accurate diagnosis is the foundation that everything else builds on: the avoidance strategy, the emergency plan, the school action plan, the decision about whether to pursue immunotherapy. Getting it right matters. Our clinic provides comprehensive food allergy evaluation including skin testing, blood work, component testing, and supervised oral food challenges for patients in the Waco area and throughout Central Texas.