The diarrhea may be accompanied by abdominal cramps, nausea, vomiting, fever, blood in the stool or weakness. Diarrhea also can have non-infectious causes. For example, most people with AIDS are lactose intolerant, which means they cannot digest lactose, a milk sugar. When they eat dairy products such as milk, cheese or ice cream they may develop diarrhea, cramping and gas. It is important to determine the cause of diarrhea so that the best treatment can be offered.
Doctors examine stool samples to determine whether diarrhea-causing organisms are present.
Doctors also may need to take small samples of tissue from the stomach or intestines to detect diarrhea-causing organisms or determine if cancer is present. If doctors identify an organism as the cause of a person's diarrhea, they prescribe the antibiotics known to be effective against that organism. There is no established treatment to combat diarrhea caused by Cryptosporidium or micro-sporidia. However, in some people with AIDS, Crypto-sporidium diarrhea goes away without treatment. Whether or not a microbe can be identified as the cause of diarrhea, patients should receive symptomatic treatment such as antidiarrheal agents, and fluids and nutrients by mouth or through a vein to replace what is expelled in their diarrhea.