It is possible to experience diarrhea after eating mayonnaise, especially if bacteria that has grown on it is ingested. If that is the case you will want to throw it out immediately. It is important to pay close attention to the expiration date of all of the foods you have in your kitchen so you can make sure not to eat it past that point.
Uncooked foods such as mayonnaise, salads, and even ice cream can potentially have bacteria on it which can cause diarrhea alone with stomach cramping and bloating. Those who have an allergic reaction to mayonnaise may also experience diarrhea along with other symptoms. Certain people who are lactose intolerant can get diarrhea from eating certain foods like mayonnaise which has eggs in it.