HIV positive people should report all side effects, even minor ones, to their doctor. People should not stop taking the drugs or change drug doses without a doctor's approval. The most common side effects of anti-HIV drugs involve the stomach and the intestines. These are known as gastrointestinal side effects. Gastrointestinal side effects include cramps, nausea, vomiting and diarrhea.
Some people also develop constipation, heartburn, and gas.
Some anti-HIV drugs are more likely to cause gastrointestinal side effects than others. For example, the protease inhibitor drug nelfinavir causes diarrhea more often than the other protease inhibitors. The nucleoside analog drug ddI can also cause stomach upset. Managing gastrointestinal side effects is important. If diarrhea and vomiting are severe and prolonged, they can affect the body's ability to absorb drugs and food nutrients.