A hypodermic needle-exchange program is a sometimes controversial social policy, based on the philosophy of harm reduction where injection drug users can obtain hypodermic needles and associated injection equipment at little or no cost. These programs are called "exchanges" because many require exchanging used needles for an equal number of new needles. In addition to sterile needles, syringe exchange programs typically offer other services such as: HIV and Hepatitis C testing; alcohol swabs; bleach and sterile water; aluminum "cookers"; containers for needles and many other items.

In the United States around 1/5 of all new HIV infections and the vast majority of Hepatitis C infections are the result of injection drug use. Dozens of studies have shown needle exchanges to be effective at preventing the spread of HIV and Hepatitis C. Needle exchange programs are supported by the Center for Disease Control and the National Institute of Health. The National Institute of Health estimates that in the United States, between fifteen and twenty percent of injection drug users have HIV and at least seventy percent have hepatitis C. The presence of needle exchange programs has been attributed to a reduction of high-risk injection behavior by up to 74%.

Needle-exchange programs can be traced back to informal activities undertaken during the 1970s, however the idea is likely to have been discovered a number of times in different locations. The first identifiable needle distribution service was undertaken by a private pharmacist in Scotland (1982 to 1984). The first government-approved initiative was undertaken in the early to mid 1980s, with other initiatives following closely. While the initial Dutch program was motivated by concerns regarding an outbreak of hepatitis A, the AIDS pandemic motivated the rapid adoption of these programs around the world. This reflects the pragmatic response to the pandemic undertaken by some governments, and encapsulated in the harm reduction / minimization philosophy.

The provision of a needle exchange therefore provides a social benefit in reducing health costs and also provides a means to dispose of used needles in a safe manner. In Australia, these programs are credited with maintaining a very low rate of HIV infections among injecting drug users. These benefits have led to an expansion of these programs in most jurisdictions that have introduced them, aiming to increase geographical coverage, but also the availability of these services out of hours. Vending machines which automatically dispense for_exchange.html" target="_blank">injecting equipment "pack" have been successfully introduced in a number of locations.

Other benefits of these programs include being a first point of contact for drug treatment, access to health and counseling service referrals, the provision of up-to-date information about safe injecting practices, and as a means for data collection from injecting drug users about their behavior and/or drug use patterns.

These services can take on a wide range of configurations:

• Primary needle and syringe program ("stand alone" service)
• Secondary needle and syringe program (such as incorporated within a pharmacy or health service)
• Mobile or on-call Service
• Dispensing machine distribution ("vending machine")
• Peer service: distribution networks
• Peer service: "flooding" or mass distribution
• Peer service: underground
• Prison-based facilities
• Distribution of bleach or other cleaning equipment (rather than needles and syringes)
• Ad hoc or informal distribution

Countries where these programs exist include: Australia, Brazil, Canada, The Netherlands, _New Zealand, Portugal, Spain, Switzerland, United Kingdom, Islamic Republic of Iran, and the United States; however in the United States such programs may not receive federal funding.

The provision of needle-exchange programs is opposed by certain groups on a wide range of grounds. These can include:

• That the programs represents a weakening of the "War on Drugs" (or equivalent) policy;
• That the programs encourage drug use;
• The services attract crime to an area;
• That the permanent location of such services may lower surrounding property values;
• There will be an increase in discarded injecting equipment around the service; and/or
• The services build and/or strengthen social networks of injectors and undermine treatment or diversion.

Each of these concerns have varying degrees of validity, though a number of meta-analysis of studies from around the world give mixed results. The methodology of such studies is under debate. European studies have found the provision of needles does not cause a rise in drug use. These findings have been endorsed by, among others, former United States Surgeon General Dr. Davis Satcher, former Director of the National Institutes of Health Dr. Harold Varmus, and former Secretary of the Department of Health and Human Services, Donna Shalala.

Regardless of this evidence, the use of federal funds for needle-exchange programs was banned in the United States of America in 1988. Most U.S. states criminalize the possession of needles without a prescription, even going so far as to arrest people as they leave private needle-exchange facilities . Nonetheless, every state in the United States has a program that supports needle exchange in some form or the purchase of new needles without a prescription at pharmacies.

These programs were introduced during the Clinton Administration but were disbanded following negative public reactions to the initiatives. Covert programs still exist within the United States.