Pollen food syndrome, also called oral allergy syndrome, occurs when the immune system mistakes proteins in certain raw plant foods for similar proteins in pollen. It is most common in people with hay fever.
Symptoms
Symptoms usually start within minutes of eating a raw trigger food and remain around the lips, mouth or throat. They can include itching, tingling and mild swelling. Fresh fruits, raw vegetables and some nuts are common triggers. Many people tolerate the same food when it is thoroughly cooked because heating changes the relevant proteins.
When to Get Emergency Help
Call your local emergency number for breathing difficulty, widespread hives, severe throat swelling, repeated vomiting, dizziness or collapse. Reactions involving nuts, cooked foods or symptoms beyond the mouth require medical assessment because another type of food allergy may be present.
Diagnosis
Diagnosis is based on hay fever history, the exact food, whether it was raw or cooked and the timing of symptoms. Skin prick or specific IgE blood tests may be used. A supervised food challenge is sometimes needed when the diagnosis is uncertain.
Management
Avoid the raw foods that cause symptoms and discuss safe cooked forms with an allergy professional. Do not exclude large groups of fruits and vegetables unnecessarily. A dietitian can help if several foods are avoided. People with a history of more serious reactions need an individual emergency plan.
Sources
Reviewed 28 August 2026.