A small amount of room-temperature watermelon and cola will generally not cause diarrhea, but if you eat watermelon and cola that is cold or eat too much of it, it is likely to cause diarrhea. Watermelon contains a lot of water and vitamins, but also contains trace elements, such as phosphorus, iron, and sugar. Cola belongs to carbonated drinks, mainly made of water, sugar and food additives, etc. Generally speaking, there is no match between these two foods, the two can be eaten together in small amounts, generally does not cause diarrhea. If the watermelon and cola is too cold, it will make the stomach and intestines stimulated, resulting in gastrointestinal peristalsis accelerated, may cause diarrhea symptoms. Watermelon and cola eat too much, and the high sugar content of watermelon and cola will also lead to increased gastrointestinal burden due to a large amount of water intake, so that the food can not be digested and absorbed, thus causing symptoms of diarrhea. If you have diarrhea after eating watermelon and cola, it is recommended that you go to the hospital as soon as possible for treatment under the guidance of a doctor.