If you’ve ever had itching, hives, or swelling in your lips, mouth, or tongue after eating a piece of fresh fruit or a vegetable --and you also have an allergy to pollen --you may have a condition called oral allergy syndrome, or OAS.
What causes OAS?
Your body’s immune system helps keep you healthy by fighting off invaders like germs. When the body mistakes something harmless, such as dust or pollen for an invader, it produces a substance that causes swelling, hives, and sneezing. When this occurs, a person is said to have an allergy.
Pollen is the fine powder made by many plants. Up to 70 percent of people who have pollen allergies also have OAS. That’s because some of the proteins in fruit and vegetables are so much like proteins in the pollen, the body gets confused and causes an allergic reaction to the fruit or vegetable, too.
Which foods are linked to which pollens?
Daniel More, MD, takes care of people with allergies. In an article on about.com, he says that people with an allergy to one of the pollens listed below often get signs of OAS when they eat the fresh fruits or vegetables listed next to it:
- Ragweed - Melons, bananas, cucumbers, and zucchini
- Birch tree - Potatoes, carrots, cherries, celery, apples, pears, plums, peaches, parsnip, kiwi, hazelnuts, and apricots
- Mugwort weed - Celery, carrots, and some spices
- Grasses - Tomatoes, potatoes, and peaches
Allergic reactions to the foods are likely to happen more often and to be worse during the season in which the pollen is found.
What can you do if you have OAS?
- Cooking the fruit or vegetable breaks up the protein that causes the allergy. Most people who get OAS when they eat a raw apple, for example, have no problem eating it when it’s cooked.
- Peeling the fruit or vegetable may help.
- A medicine called an antihistamine can help if you have an allergic reaction.
- If your OAS is causing big problems, your doctor might give you allergy shots for the related pollen.
- It the symptoms are severe, it is a good idea not to eat the raw fruit or vegetable at all. Some allergic reactions can be very bad. Get to the emergency room if you have low blood pressure, vomiting, diarrhea, or trouble breathing.