Cocaine is an illegal stimulant drug that is made from the leaves of the South American coca shrub. It comes in the form of a white powder, which is usually snorted into the nose. It provides a short-lived feeling of excitement, exhilaration and self-confidence. 

Crack is a derivative of cocaine that is smoked.

With regular use, cocaine can cause anxiety, paranoia and a tolerance for the drug, meaning that larger doses have to be taken to achieve a similar high. Long-term use of cocaine can cause psychological dependence, anxiety, depression, psychosis, aggression, weight loss and malnutrition. It can also cause heart problems including heart attack, angina, irregular heartbeat, and inflammation and enlargement of the heart. 

Cocaine does not appear to interact with any anti-HIV drugs, as the drugs are metabolised through different pathways. 

Experiments conducted in HIV-infected mice found that mice exposed to cocaine had far fewer CD4 T-cells than mice not given the drug, more cells infected with HIV and higher viral loads, possibly through increasing the levels of HIV receptors on T-cells^[1]. Cocaine can also increase HIV replication in human cells in the test tube, suggesting that HIV disease may progress faster in regular cocaine users^[2]. However, this has not been observed in all studies of HIV-infected patients^[3]. 

Animal and cell culture studies have also suggested that cocaine can increase the rates of nerve cell death in the brain and disrupt the blood-brain barrier, increasing the risk of HIV-related dementia^[4][5]. However, a study of cocaine users failed to find any additional impairment in neuropsychological function caused by the drug over that caused by HIV itself^[6].

Cocaine can also worsen or accelerate the hardening of the arteries that can occur with HIV infection or treatment, putting users at risk of heart attacks and strokes^[7].

As with other drugs of abuse, cocaine or crack use can impair adherence to HIV treatment^[8].