Food Allergy or Oral Allergy Syndrome? Learn the Difference.

Food allergies are a buzzworthy topic and lately, they’ve been front page news. This media coverage spreads both awareness and fear, making people  more aware of what they’re eating and how it makes them feel. Mouth itching and tingling can be due to two different allergy-related conditions. Before you self-diagnose or avoid food groups altogether, know the difference between food allergy and Oral Allergy Syndrome (OAS).

Food Allergy

A food allergy is diagnosed by patient history, skin prick testing and blood testing to determine true IgE response to specific foods.

To cause a reaction, the food must first go through the digestive system. Touching or smelling the food won’t typically cause a reaction. Reactions can be mild like mouth itching and tingling, but can also be very severe, presenting symptoms throughout the entire body, including anaphylaxis. Reactions can occur up to 2 hours after eating the food, and other people have delayed reactions 4-6 hours after ingesting the food.

As for treatment, some people choose to avoid problem foods. The allergy patients I see at Allergy Associates of La Crosse slowly build tolerance to their offending food allergies to avoid reactions with sublingual immunotherapy for an added layer of safety. After successful treatment, some are able to safely re-introduce the problem food, and for others, it may add a layer of safety to prevent life-threatening reactions from accidental exposure.

Oral Allergy Syndrome (OAS)

For people with an environmental allergy – like tree, grass, or a weed – they can experience reactions to certain raw fruits and vegetables. OAS isn’t a direct reaction to a food, but a complication with underlying environmental allergy. Because the protein structure in pollen and some foods are similar, during peak allergy season, the body may see the similar protein structures in raw fruits and vegetables as a threat and react.

The symptoms aren’t systemic, typically just itching or tingling in the mouth, although some may see slightly more severe symptoms. Symptoms typically occur fairly quick, within 5 to 30 minutes.

To avoid OAS symptoms, people can treat the cause of their environmental allergies with sublingual immunotherapy, manage their symptoms with an antihistamine, or cook fresh fruits and vegetables fully to break down the problematic protein structures.

Ragweed and Oral Allergy Syndrome

Ragweed season is slowing down across the country, but the millions of Americans that felt symptoms with ragweed exposure this season may have also experienced OAS. Here are the foods that typically cause reactions:

  • Banana
  • Melons (cantaloupe, honeydew, watermelon)
  • Peach
  • Cucumber
  • Zucchini

The biggest adjustment with food allergies, and any situation where a food has to be eliminated, is replacing the nutrients from the foods the person is now missing in their diet. OAS is the same way.

The foods that cause OAS symptoms for those with ragweed allergy contain many common nutrients. If eliminating one – or more – of the foods above, try to incorporate a few of these replacements into your meals each day:

  • Vitamin C: Bell peppers, citrus fruits, strawberries, kiwi
  • Fiber: Whole grains
  • Vitamin A: Sweet potato, carrot, apricot, broccoli
  • Manganese: Spinach

Seeking more information from a registered dietitian can help ensure your diet is up to par amid dietary changes. You can also learn more about oral allergy syndrome and treatment here.

By Emily Melby, RDN, Allergy Associates of La Crosse