Indigestion, also known as dyspepsia or upset stomach, is a condition of impaired digestion. Symptoms may include upper abdominal fullness, heartburn, nausea, belching, or upper abdominal pain. People may also experience feeling full earlier than expected when eating. Dyspepsia is a common problem and is frequently caused by gastroesophageal reflux disease (GERD) or gastritis.In a small minority of cases it may be the first symptom of peptic ulcer disease (an ulcer of the stomach or duodenum) and, occasionally, cancer. Hence, unexplained newly onset dyspepsia in people over 55 or the presence of other alarming symptoms may require further investigations. In those who are older or with worrisome symptoms such as trouble swallowing, weight loss, or blood loss endoscopy is recommended.Otherwise testing for H. pylori followed by treatment of the infection if present is reasonable.Indigestion is common. Functional indigestion (previously called nonulcer dyspepsia) is indigestion without evidence of underlying disease. Functional indigestion is estimated to affect about 15% of the general population in western countries.