Eat pineapple after both sides of the mouth ache generally consider patients with sensitive body, itself suffers from keratitis, mouth ulcers and other diseases caused by, usually with eating pineapple has nothing to do. 1. Sensitive body: pineapple contains some pineapple protease and biological glycosides substances, will produce oral mucosa and mouth corner stimulation, for these two ingredients sensitive people eat pineapple will have mouth corner pain. 2. Keratitis: refers to the corners of the mouth of the inflammatory reaction, mainly manifested in the corners of the mouth redness, vesicles, scabs, in eating pineapple will produce stimulation of the corners of the mouth, can be accompanied by easy to open the mouth bleeding, eating, talking are affected by the situation. 3. Mouth ulcers: due to inattention to eating habits and vitamin deficiency. Due to the destruction of the mucous membrane of the oral cavity, defects formed in the depression, the oral mucosa can appear round, oval ulcers with pain, when eating pineapple will also appear in the corners of the mouth pain performance. Need to go to the hospital, let the doctor detailed examination to further confirm the diagnosis, they can not randomly use drugs.