If you notice that you develop an upset stomach every time you eat grilled cheese, you should avoid eating that food until you can be seen by your doctor. FamilyDoctor.org states that the most common causes of dyspepsia, the medical term for upset stomach, are peptic ulcers and gastroesophageal reflux disease. Grilled cheese sandwiches are high in fat and contain lactose, which may cause upset stomach from some people.
While eating will sometimes help alleviate ulcer pain, some foods may aggravate the lining of the digestive system. Eating foods that are high in fat and difficult to digest may cause a sour stomach or stomach pain. Peptic ulcers are open sores that develop in the lining of the digestive system, in the stomach, esophagus or opening of the small intestines. Common causes of peptic ulcers include an infection of the H. pylori bacteria, tobacco use, alcohol abuse and the use of anti-inflammatory pain reliever on a daily basis.
Gastroesophageal Reflux Disease
Another common cause of an upset stomach after eating a grilled cheese sandwich is gastroesophageal reflux disease, also called GERD. This condition occurs when you develop heartburn more than twice a week. The symptoms of GERD are the result of chronic backflow of stomach acid into your esophagus. The acid can erode and irritate the soft tissues, leaving a burning and painful sensation in your upper-abdomen and lower chest. Other symptoms may include coughing, wheezing, sore throat, hoarseness, hiccups and trouble swallowing, according to the National Digestive Diseases Information Clearinghouse.
The butter and cheese used to make grilled cheese both contain a sugar found in dairy products called lactose. This complex sugar needs to be broken down in the small intestines by a digestive enzyme, lactase. If your body doesn't create enough of this enzyme, the lactose will go undigested and trigger gas, bloating, nausea and diarrhea within 20 to 30 minutes after eating the grilled cheese. These symptoms may be prevented by taking an over-the-counter enzyme supplement with your first bite of the sandwich. Talk with your doctor before using this medication.
Various digestive conditions can cause an upset stomach after eating grilled cheese. Common conditions include gallbladder disease, pancreatitis, irritable bowel syndrome, Crohn's disease and celiac disease. If you have one or more of these conditions you should avoid eating grilled cheese.