Nausea is usually caused by stress, chronic gastritis, functional dyspepsia and other factors. 1. Mental stress: If you are in a state of mental tension and stress, you may experience nausea and loss of appetite, which can be relieved by soothing your mood or doing psychological counseling to alleviate the symptoms. 2. Chronic gastritis: chronic gastritis is a chronic inflammation of the gastric mucosa caused by Helicobacter pylori infection, immunity and other factors, this disease often has no obvious symptoms, but some patients will show epigastric discomfort, lack of appetite, nausea, acid reflux, diarrhea and other symptoms. 3. Functional dyspepsia: Functional dyspepsia is a kind of functional gastrointestinal disease, and its typical manifestation is epigastric fullness, nausea and vomiting and other symptoms. Some patients are also accompanied by anxiety, irritability and other mental symptoms. If the symptoms are still not relieved after eliminating mental stress or the symptoms are too severe and have significantly affected your daily life, it is recommended to go to the hospital to find out the cause of the problem and then under the guidance of the doctor to carry out reasonable treatment.