Indigestion, also known as dyspepsia or an upset stomach, is discomfort in the upper abdomen that describes certain symptoms such as belly pain and a feeling of fullness soon after eating, rather than a specific disease. Indigestion can be caused by various factors, including:

• Lifestyle: Overeating or eating too quickly, fatty, greasy or spicy foods, too much caffeine, alcohol, chocolate or carbonated beverages, and smoking.

• Medications: Certain antibiotics, pain relievers, and iron supplements.

• Medical conditions: Inflammation of the stomach, called gastritis, peptic ulcers, celiac disease, gallstones, constipation, pancreas inflammation, called pancreatitis, stomach cancer, intestinal blockage, reduced blood flow in the intestine, called intestinal ischemia, diabetes, thyroid disease, and pregnancy.

• Functional dyspepsia: A condition known as functional or nonulcer dyspepsia, which is related to irritable bowel syndrome, is a very common cause of indigestion.

Indigestion is often a sign of an underlying problem, such as gastroesophageal reflux disease (GERD), ulcers, or gallbladder disease, rather than a condition of its own. Indigestion that lasts longer than one meal, or that comes and goes chronically, is often less simple, and there may be a variety of factors involved. If you have indigestion and any of the following symptoms, you may have a more serious condition and should see a doctor right away: black, tarlike stools, bloody vomit, difficulty swallowing or painful swallowing, frequent vomiting, losing weight without trying, pain in your chest, jaw, neck, or arm, severe and constant pain in your abdomen, shortness of breath, sweating, yellowing of your eyes or skin.