Heroin users are at risk for contracting HIV, hepatitis C (HCV), and other infectious diseases, through sharing and reuse of syringes and injection paraphernalia that have been used by infected individuals, or through unprotected sexual contact with an infected person. Injection drug users (IDUs) represent the highest risk group for acquiring HCV infection; an estimated 70 to 80 percent of the 35,000 new HCV infections occurring in the United States each year are among IDUs.

NIDA-funded research has found that drug abusers can change the behaviors that put them at risk for contracting HIV through drug abuse treatment, prevention, and community-based outreach programs. They can eliminate drug use, drug-related risk behaviors such as needle sharing, unsafe sexual practices, and, in turn, the risk of exposure to HIV/AIDS and other infectious diseases. Drug abuse prevention and treatment are highly effective in preventing the spread of HIV.