Frequent diarrhea is not necessarily AIDS. The most common causes of diarrhea are diseases of the gastrointestinal tract itself, such as various intestinal inflammatory diseases, tuberculosis, and problems with the immune system, all of which can lead to diarrhea. Although AIDS can also cause diarrhea, it is mainly caused by damage to the immune system and can result in a variety of opportunistic infections, leading to nausea, vomiting, malabsorption, prolonged diarrhea, and even gastrointestinal bleeding. However, such patients usually have a history of high-risk exposure, and without a history of high-risk exposure, AIDS is not usually suspected. Patients can do AIDS-related tests to rule out the diagnosis. If not, a gastroscopy as well as a colonoscopy is also needed to rule out diseases of the digestive system itself.