Oral Allergy Syndrome (Pollen-Food Cross-reactivity)


Do you have seasonal allergies? Do you get an itchy mouth or throat after eating raw fruits, vegetables and/or nuts? If so, you may be suffering from oral allergy syndrome.

Plant Based Foods

This reaction occurs because the proteins found in plant-based foods are very similar to those found in pollen. This confuses the immune system and can cause a cross reaction resulting in oral allergy syndrome.

Allergic Reactions

This is a form of contact allergic reaction causing itchiness or swelling of the mouth, face, lips, tongue and throat usually immediately after eating the culprit food.

It is generally considered a mild form of food allergy. Rarely does this cause severe throat swelling leading to difficulty swallowing, breathing or progressing into anaphylaxis however there is a small risk and thus is advised to practice caution when eating foods that trigger this.

Why It Happens

Most of the allergens are acid and heat labile, whatever food is swallowed is typically rapidly degraded by digestive enzymes and gastric acid. Therefore most patients can tolerate the cooked or processed versions of the foods triggering symptoms.

Treatment Options

It is advised to avoid eating these raw foods especially during high allergy season. Peeling the food before eating may be helpful as well.

Some studies have shown that treatment with allergy shots can improve the symptoms of oral allergy syndrome.

Here is a helpful table showing the possible cross-reactivity that can occur with this common condition.

Cross-reactivity Graphic