Nausea when smelling fumes may be caused by bad odor stimulating the mucous membrane of the digestive tract; for young, sexually active women with a history of menopause, this symptom may be caused by early pregnancy; in addition, it may be caused by chronic gastritis, hepatitis, cholecystitis, cholelithiasis, digestive disorders, or psychological factors. The cause can be clarified by checking blood hcg, liver and kidney function, gastrointestinal ultrasound, gastroscopy, etc.