Pollen food allergy syndrome (PFAS) is a food allergy that manifests as hypersensitivity symptoms of the oropharyngeal mucosa on ingesting specific foods, and findings resemble herpetic gingivostomatitis. Few reports of PFAS caused by consuming radishes are found in the literature. A 31-year-old man presented to our department with stomatitis and pharyngeal pain. He had no history of allergies. Herpetic gingivostomatitis was suspected. He was admitted to the emergency room a few days later complaining of oral and epigastric pain. Symptoms were similar to those reported previously. He reported frequently consuming raw Japanese radish (Raphans sativus L.) which gave rise to his symptoms. Japanese radish was suspected as the allergen. The skin-prick test confirmed the diagnosis of PFAS. PFAS can be diagnosed easily once the food-causing symptoms are identified. Upon encountering widespread erosion in the oral cavity, it is essential to consider PFAS as the possible cause.