Heroin Use and Infections

3 Common Modes of Transmission

Man holding needle in a park with his head down

Matthew Heptinstall / Getty Images

Rates of heroin use have been climbing in the United States over the last decade. Beyond deaths directly from overdoses and other drug-related risks, heroin use is also associated with infections, which may directly or indirectly affect people long after the drug has cleared the system. Treatment for addiction may reduce the risk of overdose, but some infections may remain.

The fact that heroin is often injected is the reason it can cause infections to spread. Some individuals may start by abusing prescription drugs before moving to less expensive heroin. This move may be from a drug that is not injected to a drug that is.

There are three sources of transmission when heroin is injected:

  • Shared needles and other injecting equipment, leading to infections transmitted by blood
  • Non-sterile injection practices, leading to infections from bacteria on the skin
  • Contaminated heroin, leading to some uncommon infections

Shared Injecting Equipment

Shared injecting equipment is a primary mode of transmission for many communicable diseases.

Hepatitis C

Hepatitis C is a virus that causes liver damage. It can occur with the appearance of acute symptoms, but most people do not even know they have the disease until decades later, when the liver damage has progressed. Hepatitis C is most often spread by shared injecting equipment.

According to one estimate, roughly 38% of all hepatitis C infections worldwide are related to injecting drug use, while 81% of cases in North America are attributed to shared needles.

There are approximately 2.4 million cases of chronic hepatitis C in the United States. Most infections occurred in the 1970s and 1980s before blood supplies were routinely tested for the virus.

Hepatitis B

Hepatitis B is a virus unrelated to hepatitis C, but it is also transmitted by sharing needles and causes liver damage. In addition, hepatitis B can spread through having unprotected sex with an infected partner as a result of impaired judgment while under the influence of drugs. Hepatitis B infection in people who inject drugs has been estimated to be between 5% and 10% in North America. There is a vaccine available for hepatitis B.


HIV can be spread through a variety of ways, including sex, mother-to-child transmission, and shared needles. Worldwide, it is thought that about 30% of HIV infections outside of sub-Saharan Africa are from shared needles and injection equipment.

In fact, in countries like Russia, injecting drug use is today the primary mode of HIV transmission, unlike in the United States, where the sexual transmission of HIV predominates.

Lack of Sterile Technique

There are a number of infections that spread because the needles, though not shared, are used without sterile technique. The use of needles requires practice and protocols to avoid spreading infections. Otherwise, needles pierce through skin that is normally covered in bacteria, taking the bacteria under the skin and into the bloodstream.

One of the most common forms of bacteria spread by shared needles is methicillin-resistant Staphylococcus aureus (MRSA), a highly resistant infection seen in alarming numbers in both heroin and crystal methamphetamine users.

There are other infections caused by bacteria, such as Group A streptococcus. These infections can spread through skin-popping, leading to abscesses, boils, and cellulitis. Some types of cellulitis can be mild, while others can lead to severe complications like necrotizing fasciitis.

Intravenous drug use can send these bacteria directly into the bloodstream. This can cause an infection in the blood, leading to sepsis. The bacteria can affect other parts of the body, including heart valves (endocarditis), bones (osteomyelitis), and joints (septic arthritis).

Contaminated Drugs

Injected drugs are not usually "pure" but are generally mixed with other substances, some of which may include other harmful microorganisms. Some injected drug users mix their drugs with unsterile tap water, leading to infections from microbes like Pseudomonas and Corynebacterium diphtheriae.


Botulism is a rare bacterial infection that is potentially fatal but is now uncommon in the United States because of safety measures in food canning and preparation. The same cannot be said for injected drug use.

The bacterium Clostridium botulinum regularly contaminates heroin, especially "black tar heroin." It can be spread by skin popping or intravenous drug use, causing weakness, drooping eyelids, blurred vision, and difficulty swallowing.

Because botulism is a rare infection, diagnosis may be delayed. However, because the bacterial toxins can contaminate entire batches of heroin, there will often be a localized outbreak recognized by public health officials.


Tetanus spores can contaminate heroin, either during production and in the injection process itself. Clostridium tetani are found naturally in the environment, such as in dirt or on rusty equipment. In the United Kingdom, a tetanus outbreak was directly linked to heroin injections in 2003 to 2004.

Other Causes

Other infections caused by spores have also been reported, including Bacillus cereus (a relative of Bacillus anthracis), Clostridium sordellii (a relative of Clostridium botulinum and Clostridium tetani), and anthrax (caused by Bacillus anthracis).

For help with drug addiction, call the Substance Abuse and Mental Health Services Administration (SAMHSA) National Helpline at 1-800-662-HELP.

7 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  2. Degenhardt L, et al. Estimating the Burden of Disease Attributable to Injecting Drug Use as a Risk Factor for HIV, Hepatitis C, and Hepatitis B: Findings from the Global Burden of Disease Study 2013. Lancet Infect Dis. 2016 Dec;16(12):1385-1398. doi:10.1016/S1473-3099(16)30325-5.

  3. Centers for Disease Control and Prevention. CDC Estimates Nearly 2.4 Million Americans Living with Hepatitis C. Press release.

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By Megan Coffee, MD
Megan Coffee, MD, PhD, is a clinician specializing in infectious disease research and an attending clinical assistant professor of medicine.