According to the Southwest Allergy and Asthma Center, one symptom of a rice allergy is usually hives (a red rash that itches) that manifest after a few minutes of a person eating rice or a food with rice. However, symptoms do not necessarily involve hives and include vomiting, diarrhea, bloody stools and, in more serious cases, stunted growth or drastic weight loss.
If hives occur, they can become part of anaphylaxis, which is a severe allergic reaction to rice. Symptoms of anaphylaxis include wheezing or breathing issues; cramping in the stomach; nausea; diarrhea; swelling of the throat, face or mouth; low blood pressure and fainting. Rice allergies can also make eczema worse for a few hours up to a few days.
WebMD points out that rice allergies are more common in Japan, where people frequently eat rice. The Southwest Allergy and Asthma Center says that most children with rice allergies outgrow them by the time they enter school. People who have rice allergies should not only avoid eating rice, but they should avoid all foods that has touched rice or come into contact with it. Mothers who are breast-feeding a child who has a rice allergy should also not eat rice.