Oral Allergy Syndrome: Why My Mouth Itches When Eating Fruit

When you experience numb lips, itchy lip corners, or an itchy palate after eating fresh fruit, most of them are caused by oral allergy syndrome. It also has a more straightforward name called pollen-food allergy syndrome. The essence is that the immune system is "blind to the wrong person" - it is very common. The protein structure in allergenic pollen is highly similar to the protein in some fresh fruits and vegetables. The immune antibodies originally activated by pollen mistakenly think that they are invading allergens when they encounter this kind of fruit and vegetable protein, and directly trigger an immune attack on the oral mucosa. Therefore, symptoms are mostly concentrated in the oral area first.

I met a girl in her 20s at the clinic last week. She suffers from allergic rhinitis every year during the birch pollen season in March and April. She took a bite of a nectarine she just bought a few days ago. Her lips were numb in less than two minutes, and her palate was so itchy that she couldn't help but rub it with the tip of her tongue. After a few minutes, she thought it was because the peach hairs had not been washed, so she peeled it cleanly and ate half a piece. The result was that she was still itchy. After checking the allergens, she found out that it was not the peach at all. It was the birch pollen antibodies in her body that mistook the protein in the peach as pollen. Not only peaches, but common fruits, vegetables and nuts such as apples, cherries, kiwis, and almonds are all highly allergic foods for people allergic to birch pollen. People allergic to ragweed and mugwort are also prone to such reactions when eating watermelon, cantaloupe, bananas, and mangoes.

Of course, not all cases of itchy mouth after eating fruit should be labeled as oral allergy syndrome. For example, many people feel sore and itchy in the mouth after eating pineapple. After soaking in salt water and then eating, it will be fine. This is actually caused by the protease in the pineapple stimulating the mucous membranes and is not an allergy. ； Some people are allergic to preservatives, pesticide residues or fruit wax on the fruit's skin. They feel no discomfort after eating them after thoroughly peeling and rinsing them. This has nothing to do with this syndrome.

There is currently no completely unified statement in the industry about how to deal with this type of allergy. If you only have a slight itchiness that subsides in three to five minutes after eating, and there is no rash, stomachache, or throat tightness, many doctors will suggest that you don’t need to completely avoid eating it. You can just heat and cook the corresponding fruit. Whether it is steamed apples, boiled pears, or grilled peaches, when the temperature rises, the allergenic proteins will be denatured and inactivated. The immune system will not recognize it, so it will not cause a tantrum, and you can still eat it. ； Some people would be more cautious. Especially for patients who have had swollen lips and foreign body sensation in the throat before, it is best to actively avoid the corresponding fresh fruits and vegetables. After all, there have been very few clinical cases where it was just a slight itching of the mouth at first, but then a severe systemic allergic reaction suddenly occurred when eating.

If you often have itchy mouth after eating certain types of fresh fruits and vegetables, and you have a history of seasonal pollen allergy or allergic rhinitis, you can find out by taking the time to go to the allergy department to check the allergens. There is no need to force yourself or simply give up all fruits. The gain outweighs the loss.