Oral allergy syndrome (OAS) is also known as pollen-food allergy syndrome (PFS) or pollen fruit syndrome (PFS). Oral allergy syndrome (OAS) is a sensitivity to plant-based foods. Normally, this shows up as a redness or swelling of the lips, tongue, mouth, and throat along with difficulty breathing or swallowing. Anaphylaxis is also possible but tends to be rare. Usually, symptoms do not involve gastrointestinal problems, such as diarrhoea or nausea. it is more common in those with a pollen allergy, and these allergies pertain to raw fruits, raw vegetables, nuts, and spices rather than these items cooked.