If you eat too many pineapples, you will have the following symptoms. First, pineapple contains certain glucosides, which has a certain stimulating effect on human skin. Eating a small amount will not cause a reaction, but eating too much will cause itching or allergies. Second, pineapple contains a lot of plant acids, which are corrosive. Eating too much will make your tongue numb and your mouth ulcer. Thirdly, the plant acid in pineapple has a strong stimulating effect on gastrointestinal tract, which can promote the secretion of gastric juice, easily damage the stomach and cause acute gastroenteritis.