Nausea is an unpleasant sensation of queasiness or discomfort in the stomach that often precedes the urge to vomit. It can result from a wide range of causes, including gastrointestinal infections, food poisoning, motion sickness, pregnancy, medication side effects, migraines, anxiety, or systemic illnesses. Nausea may occur alone or be accompanied by vomiting, abdominal pain, dizziness, sweating, or loss of appetite. In most cases, it is temporary and resolves once the underlying trigger subsides. However, persistent, severe, or unexplained nausea—especially when associated with dehydration, severe pain, or neurological symptoms—requires medical evaluation to determine the underlying cause.