Allergy Updates

Every spring, Wisconsin allergists hear the same story from patients. A child or adult who has been eating apples, carrots, or raw celery for years without any issue suddenly experiences a strange tingling or itching sensation in their mouth when they eat these foods during pollen season. Their parents, understandably alarmed, wonder whether a new food allergy has developed. In many cases, it hasn’t. What’s happening is Oral Allergy Syndrome (OAS) — also called Pollen-Food Allergy Syndrome — and it’s one of the most frequently misunderstood conditions in the allergy world. Understanding OAS matters for two reasons. First, it can cause real discomfort and, in rare cases, more serious reactions. Second, it is regularly confused with true food allergy, leading to unnecessary dietary restrictions, missed diagnoses, and — in the opposite direction — dismissal of symptoms that genuinely need attention. Getting the distinction right requires proper evaluation. If you’re experiencing new food-related symptoms this spring, our team at Wisconsin Food Allergy can help you determine whether you’re dealing with OAS or a true food allergy. What Is Oral Allergy Syndrome? Oral Allergy Syndrome is a form of contact allergic reaction that affects the mouth, lips, tongue, and throat. It occurs in people who are already sensitized to certain airborne pollen. The immune system, having learned to recognize pollen proteins as a threat, mistakenly identifies similar proteins in certain raw fruits and vegetables as the same threat and reacts accordingly. Birch-related OAS is the most common form in the upper Midwest, where birch and related tree species (alder, hazel) are prevalent.This is called cross-reactivity. The proteins in the food aren’t identical to pollen proteins, but they’re similar enough in structure that the immune system treats them as equivalent. The reaction is usually localized — confined to the oral mucosa (the lining of the mouth and throat) — because the food proteins are rapidly broken down by digestive enzymes as they move past the mouth. According to the American Academy of Allergy, Asthma and Immunology (AAAAI), Oral Allergy Syndrome affects up to 70% of people with birch pollen allergy and is one of the most common allergic conditions in adults. The key distinction from true food allergy In a true IgE-mediated food allergy, the allergenic proteins in food are heat-stable and digestion-resistant. They survive cooking, processing, and the digestive process and can trigger systemic reactions anywhere in the body — hives, swelling, vomiting, and anaphylaxis. In OAS, the cross-reactive proteins are heat-labile. Cooking, pasteurizing, or even microwaving the food typically destroys these proteins, which is why many people with OAS can tolerate the cooked version of a food but not the raw version. Someone who reacts to raw apples may be able to eat applesauce. Someone who can’t eat raw carrots may be fine with cooked carrots in soup. This heat-sensitivity is one of the most useful clinical clues for distinguishing OAS from true food allergy — but it is not a reliable self-diagnostic rule. Some individuals with OAS do experience systemic reactions, and the only way to get a definitive diagnosis is through proper allergy testing. Wisconsin Food Allergy offers comprehensive allergy testing at our Kenosha, Franklin, and Oshkosh locations. The Most Common Pollen-Food Pairings in Wisconsin Different pollens cross-react with different foods. Understanding which combinations are most relevant for Wisconsin’s pollen season helps families identify patterns. Birch pollen (spring) – the most extensive cross-reactor Birch trees are common throughout Wisconsin, and birch pollen season typically runs from March through May. Birch pollen cross-reacts with a wide range of foods: Grass pollen (late spring into summer) – the seasonal overlap Wisconsin’s grass pollen season runs roughly from May through July, overlapping with late spring. Grass pollen cross-reacts with a smaller range of foods but includes: Grass pollen OAS tends to be less pronounced than birch-related OAS, but symptoms can intensify during peak grass pollen counts. Ragweed pollen (late summer to fall) – worth knowing for later While not a spring issue, ragweed is Wisconsin’s dominant fall allergen and cross-reacts with: Patients who notice mouth tingling with these foods specifically in August and September may be dealing with ragweed-related OAS. Symptoms of Oral Allergy Syndrome OAS symptoms typically begin within minutes of contact with the triggering food. They are almost always confined to the mouth and throat area. Common OAS symptoms: These symptoms usually resolve within 30 minutes of removing the food from the mouth. When OAS symptoms require urgent attention Most OAS reactions are mild and self-limiting. However, a meaningful minority of patients — particularly those with a significant underlying pollen allergy — can experience more significant reactions including throat tightening, difficulty swallowing, or systemic symptoms. Any of the following symptoms following food contact require immediate emergency attention: These symptoms indicate a potentially serious allergic reaction, not OAS. Use epinephrine if available and call 911. Do not wait to see if symptoms resolve. If you or your child has experienced any reaction beyond mild oral symptoms, please contact Wisconsin Food Allergy promptly for evaluation How OAS Is Diagnosed There is no single definitive test for OAS. Diagnosis is based on a combination of: Thorough clinical history. Your allergist will ask detailed questions about which foods trigger symptoms, whether symptoms are seasonal, and whether cooked versions of the food are tolerated. Pollen allergy testing. Skin prick tests or specific IgE blood tests can identify sensitization to birch, grass, ragweed, and other pollens. Demonstrating relevant pollen sensitization is a key part of confirming OAS. Fresh food prick test. In some cases, testing with fresh raw food extract (rather than commercial standardized extracts) provides useful diagnostic information because the heat-labile proteins are preserved. Oral food challenge (in selected cases). When the diagnosis is uncertain or when a true food allergy cannot be ruled out by history and testing, a supervised oral food challenge may be conducted in a controlled medical setting. It’s important to note that standard commercial food allergy tests can sometimes produce false positives for OAS-related foods. A positive IgE test

Food allergies in Wisconsin have become an increasingly pressing health concern across the United States. Families throughout the state are grappling with diagnoses that affect daily life, from grocery shopping to school lunches to family gatherings. Understanding why food allergy cases are rising, recognizing symptoms early, and knowing when to seek specialized care can make a significant difference in managing this growing health challenge. Understanding the Surge in Food Allergy Cases The rise in food allergies isn’t just a perception—it’s a documented trend that has medical professionals and researchers working to understand the underlying causes. Wisconsin families are experiencing this surge firsthand, with more children and adults receiving food allergy diagnoses than ever before. National vs Wisconsin-specific statistics Nationally, food allergies affect approximately 8% of children and 11% of adults, representing a substantial increase over the past two decades. Research indicates that food allergy prevalence among children increased by 50% between 1997 and 2011, and this upward trend has continued into recent years. Emergency department visits for food allergy reactions have similarly climbed, highlighting the severity and frequency of allergic episodes. In Wisconsin, the picture mirrors these national trends, though some regional variations exist. Wisconsin’s diverse population and geographic spread mean that food allergy rates can vary between urban centers like Milwaukee and Madison and more rural communities. Healthcare providers across the state report seeing more patients with multiple food allergies, a phenomenon that complicates dietary management and increases the risk of accidental exposure. Environmental and dietary factors Several environmental theories attempt to explain why food allergies are becoming more common. The “hygiene hypothesis” suggests that reduced exposure to microbes in early childhood—due to increased sanitation, smaller family sizes, and less time spent outdoors—may prevent the immune system from developing properly, making it more likely to react to harmless proteins in food. Wisconsin’s climate and environmental factors may also play a role. The state’s long winters mean children often spend extended periods indoors, potentially limiting microbial diversity exposure. Additionally, changes in dietary patterns, including increased consumption of processed foods and altered timing of food introduction during infancy, may contribute to rising allergy rates. Vitamin D deficiency has emerged as another potential factor. Wisconsin’s northern latitude means residents receive less sunlight exposure, particularly during winter months, which can lead to lower vitamin D levels. Some research suggests that vitamin D deficiency may be associated with increased food allergy risk, though more studies are needed to establish a definitive link. Early childhood exposure patterns How and when infants are introduced to allergenic foods has been a subject of evolving guidance. For years, parents were advised to delay introducing common allergens like peanuts, eggs, and fish. However, groundbreaking research has since reversed this recommendation. Current guidelines from organizations including the American Academy of Pediatrics now encourage early introduction of allergenic foods—typically around 4-6 months of age—as a strategy to prevent food allergies.  Even earlier introduction by maternal diet in utero and during breast feeding can be an added strategy.  Despite this updated guidance, many Wisconsin families remain unaware of the importance of early allergen introduction, or they feel hesitant to try it without medical supervision. This knowledge gap may contribute to continued high rates of food allergies as optimal prevention windows are missed. Common Food Allergies Seen in Wisconsin Patients While food allergies can develop to virtually any food, certain allergens are far more common than others. Understanding which foods most frequently trigger allergic reactions helps families stay vigilant and prepared. Peanut, tree nut, milk, egg The “Big Eight” food allergens account for approximately 90% of all food allergic reactions in the United States: milk, eggs, peanuts, tree nuts, soy, wheat, fish, and shellfish. Among Wisconsin patients, peanut and tree nut allergies are particularly prevalent and tend to persist into adulthood, unlike milk and egg allergies, which some children could outgrow. Peanut allergy affects approximately 2% of children and is one of the leading causes of severe, life-threatening allergic reactions. Tree nut allergies—including reactions to walnuts, cashews, almonds, and pecans—often occur alongside peanut allergies but can also develop independently. These allergies require strict avoidance, as even trace amounts can trigger serious reactions. Milk and egg allergies are most common in infants and young children. Milk allergy affects about 2-3% of infants, though some may outgrow it by age 5. Egg allergy follows a similar pattern. For Wisconsin families, managing these allergies during early childhood means carefully reading labels, finding suitable substitutes for baking and cooking, and coordinating with daycare providers and schools to ensure safe meals. Regional food patterns and hidden triggers Wisconsin’s strong dairy heritage and agricultural traditions mean that milk and dairy products are deeply embedded in the local food culture. From cheese curds to Friday fish fries with tartar sauce, navigating Wisconsin’s culinary landscape with a dairy or egg allergy presents unique challenges. Cross-contamination is a significant concern, particularly in restaurants and at social gatherings. Foods that appear safe may contain hidden allergens through shared cooking equipment, preparation surfaces, or ingredients. For example, many Wisconsin bakeries use the same equipment to prepare products containing nuts, eggs, and dairy, creating cross-contamination risks even in items that don’t list these ingredients. Seasonal considerations also matter. Wisconsin’s vibrant farmers market culture means families often purchase fresh, local foods. While this has many health benefits, it also requires vigilance in asking vendors about ingredients and potential cross-contact, as these settings may lack the detailed labeling found in commercial products. Symptoms to Watch For Recognizing the signs of an allergic reaction is critical for prompt treatment and prevention of severe complications. Food allergy symptoms can range from mild discomfort to life-threatening emergencies, and reaction severity isn’t always predictable. Mild to moderate reactions Mild to moderate allergic reactions typically begin within minutes to two hours after consuming the triggering food. Symptoms may include: While these symptoms may seem manageable, they should never be dismissed. A mild reaction on one occasion doesn’t guarantee all future reactions will be mild. Some individuals experience progressively more severe reactions