Upset stomach, also known as dyspepsia or indigestion, is a common condition that can cause discomfort in the upper abdomen. Symptoms may include bloating, nausea, vomiting, and a feeling of fullness. Upset stomach can be caused by various factors, such as overeating, eating spicy or fatty foods, stress, or infections. Treatment often involves lifestyle changes, such as eating smaller meals and avoiding trigger foods, as well as over-the-counter medications to relieve symptoms. However, persistent or severe symptoms should be evaluated by a healthcare professional.