After a large meal, such as a Thanksgiving feast, you may be surprised by some gastrointestinal upset. However, food poisoning brings much more severe and long-lasting symptoms compared to indigestion. Learn about how to identify the source of your gastrointestinal upset and when to seek medical treatment for your symptoms. Causes of Food Poisoning Food poisoning is a unique illness because, unlike many other infections and diseases, it is not contagious. Instead, you contract food ...