Oral allergy syndrome, or OAS, is an allergic reaction that usually happens only in the lips, mouth and throat. People with OAS can react to specific foods, such as some raw fruits and vegetables. When they eat those foods, they may notice itching, tingling, swelling, and redness of the lips, mouth, or throat — often within minutes.
People who are allergic to pollen are more likely to have OAS. In fact, OAS is also called pollen-food allergy syndrome. The immune system gets confused and thinks that the foods being eaten are similar to pollen that the person is allergic to. Many people with OAS can eat these same foods without any problems if they are cooked, not raw. That's because cooking changes the food enough that the immune system no longer thinks it is a threat.
OAS usually only involves mild symptoms in the mouth and throat. But, rarely, the reaction also can affect other parts of the body or cause more serious symptoms, like trouble breathing. If there's a concern that your child is at risk of a more serious reaction, your doctor might prescribe emergency medicine to always have available.
If the doctor thinks your child has OAS, they may give you a list of foods to avoid or to be careful with. The doctor also can give you other tips to make a reaction less likely, such as peeling or cooking the food before offering it to your child.