Globally, it is estimated that 296 million people used illicit drugs in 2021, which was a 23% increase from the number reported in 2011. Of the drug users in 2021, about 13 million were injection drug users. The burden of injection drug use is different in different regions of the world. About 1.3% of the adult population in Eastern Europe inject drugs while 1% in North America also inject drugs. People who inject drugs (PWID) are 35 times more likely to acquire HIV compared to those who do not inject drugs and about 12% of PWID globally live with HIV. The distribution of HIV among PWID globally is heterogeneous. Regions with the highest prevalence of HIV among PWID are Southwest Asia, with 29.3%, and Eastern Europe with 25.4%. The risk factors for HIV among PWID include the sharing of drug injection equipment such as syringes and needles, inconsistent use of condoms, the use of unsterilized injection equipment, having multiple sexual partners, and exchanging sex for drugs and money. Women who inject drugs (WWID) are 1.2 times more likely than males to have HIV, even though men are five times more likely to inject drugs than women. This gender disparity has been attributed to sex work among WWIDs, their vulnerability to abuse by law enforcement officers, and physical violence or rape.