Heroin is part of a group of drugs called opioids. It’s one of the most commonly used drugs in the United States.

According to the 2020 National Survey on Drug Use and Health:

  • Approximately 902,000 people over the age of 12 used heroin in the prior year.
  • Approximately 691,000 people over the age of 12 had heroin use disorder in the prior year.

Some people take heroin by snorting or smoking it, while others inject it under the skin or into their veins or muscles.

People who inject heroin are at an increased risk of contracting certain infections. Keep reading to learn more about how heroin use can lead to infection.

There are several ways that pathogens such as bacteria and viruses can spread from one person to another, including through blood and other bodily fluids.

Certain factors associated with heroin use can increase your risk of infection. These include:

  • Sharing or reusing needles. Previously-used needles and syringes are not sterile and can introduce bacteria and viruses into the body.
  • Reusing cottons or filters. Previously-used filters can carry pathogens like bacteria and fungi.
  • Using dirty water. Dissolving drugs in unclean water and then injecting the solution can lead to infection.
  • Unclean injection sites. If the skin is not properly cleaned before an injection, bacteria on the skin’s surface can enter the body.
  • Using certain types of drugs. Injecting black tar heroin is associated with an increased instance of infection, according to a 2021 study.
  • Other injection practices. The study cited above found that certain injection practices are more likely to cause an infection. These include:
    • injecting heroin into the skin (subcutaneously) or muscle (intramuscularly) instead of into the vein
    • pushing the contents of a syringe into the body and then out again multiple times, which is known as booting or jacking

In addition, people who inject drugs are more likely to experience other factors that increase their risk of infection, according to 2020 research.

These include unstable housing, incarceration, and sexual practices like:

  • having multiple sexual partners
  • having receptive sex without a condom
  • having sex with someone whose HIV status is unknown

According to a 2019 study, people who inject heroin have a greater risk of developing bacterial infections compared to people who inject other drugs. It’s not clear why this is the case.

Some of the most common infections associated with heroin use are described below.


Wound botulism is a rare but serious infection caused by the spores of Clostridium botulinum, a type of bacteria that lives in soil.

These spores can enter the body through an open wound and form a toxin that attacks the nervous system. Without treatment, wound botulism can be fatal.

The Centers for Disease Control and Prevention (CDC) reports that wound botulism is rare, with approximately 20 people receiving a diagnosis each year in the United States.

According to a 2019 report, black tar heroin poses an increased risk of wound botulism due to how it’s produced, transported, prepared, and injected. Several cases involved injecting black tar heroin into the skin, a practice known as skin popping.

People who have signs of wound botulism should seek emergency medical care right away. These signs include:

  • difficulty swallowing, speaking, or breathing
  • blurred vision
  • weakness


Cellulitis is a bacterial infection that affects the deeper layers of your skin. It causes redness, pain, and swelling. If left untreated, the infection could spread to your blood, joints, bones, or heart.

Cellulitis is a common complication for people who inject drugs, according to a 2020 study. Injections create a break in the skin for bacteria to enter. Poor injection hygiene practices, like sharing needles and not cleaning your skin, can increase the risk.

Cellulitis does not go away without antibiotic treatment. It’s important to seek medical care as soon as possible to minimize potential complications.


Infective endocarditis causes the inner lining of the heart, known as the endocardium, to become inflamed. It is life threatening.

Injecting heroin can put you at an increased risk of developing endocarditis. This is because bacteria and fungi can easily enter your body through an injection site and spread to your heart.

People who inject heroin are also likely to have other illnesses that compromise the immune system, such as hepatitis C (HCV) or human immunodeficiency virus (HIV).

Endocarditis is not always severe right away. Symptoms sometimes resemble those of the flu and worsen over time. Other signs can include chest pain, shortness of breath, and swelling in the legs or feet.

You should see your doctor right away if you inject heroin and have signs of an illness or infection that do not go away. Treatments for infective endocarditis include medication and surgery.

Hepatitis B

Hepatitis B (HBV) is a virus that can cause lasting liver damage. It’s spread through blood and sexual contact.

People who inject drugs like heroin are at an increased risk of contracting HBV. It can be transmitted by sharing needles and other drug injection equipment. It’s also spread through vaginal or anal sex with someone who has the virus.

There is a vaccine to prevent HBV. If you did not receive the vaccine as an infant, child, or adolescent, you can still get it as an adult.

If you think you have HBV, you should get tested by a healthcare professional as soon as possible. It may be possible to prevent an infection with medication plus a first dose of the vaccine.

Hepatitis C

Like HBV, hepatitis C (HCV) is a blood-borne virus that can cause substantial liver damage. Sharing needles and other drug injection equipment puts people who use heroin at an increased risk of contracting HCV. So do certain sexual practices.

There is currently no vaccine for HCV, but it is often curable with antiviral drugs. The first step is taking a test to see if you have it. If you inject drugs, it’s a good idea to get screened regularly for HCV.


Human immunodeficiency virus (HIV) is transmitted via contact with blood from someone who has the virus. According to the CDC, 10 percent of HIV infections in the United States occur via injection drug use.

This can happen when you share needles or other equipment with someone who has HIV. Certain sexual practices, including condomless receptive vaginal or anal sex with someone who has HIV, are also associated with an increased risk of transmission.

If you suspect you have HIV, you should see a healthcare professional to take a test. If you test positive for HIV, antiretroviral therapy is one of the main treatments to manage HIV infection in the long term.


Methicillin-resistant Staphylococcus aureus (MRSA) is a bacteria that has developed a resistance to various antibiotic drugs. MRSA infections are highly contagious and difficult to treat.

MRSA can enter the body through a break in the skin at the injection site, putting people who inject drugs like heroin at an increased risk. According to the CDC, people who inject drugs are about 16 times more likely to develop an MRSA infection than other people.

MRSA can infect the skin or spread to other parts of the body through the bloodstream. It can lead to serious complications, such as sepsis.

Doctors use oral or intravenous (IV) antibiotics to treat MRSA infections. The sooner you seek treatment, the better.

MRSA can also cause abscesses. These are pus-filled bumps that form at the injection site. People who use black tar heroin are more likely to develop abscesses, according to a 2017 study.


Osteomyelitis is a bone infection. It occurs when bacteria or fungi enter the body and attack a bone.

People who use heroin are more susceptible since injection creates a small puncture wound that microbes can enter the body through. These microbes then spread to your bone.

If you have osteomyelitis, the affected area might be swollen, red, or stiff. You might also feel unwell or have signs of an infection, like a fever or chills.

You should seek treatment right away since untreated osteomyelitis can require surgery.

Septic arthritis

Septic arthritis refers to a joint infection. In people who inject heroin, it can occur when bacteria or fungi that enter the body through an injection site spread and infect the joints.

The signs are similar to those of osteomyelitis. You might have pain, swelling, or stiffness in the affected area along with a fever, chills, fatigue, or weakness.

Septic or infectious arthritis requires swift medical treatment if you want to avoid complications. Usually, oral antibiotics or antifungal drugs are enough, but sometimes surgery is needed to remove or replace parts of the joint that have been damaged.


A bacteria called Clostridium tetani causes tetanus. When spores enter the body through a break in the skin, they can form a toxin that disables communication between the spinal cord and muscles.

Vaccination has made tetanus rare in the United States, but unvaccinated people who inject black tar heroin are at an increased risk, according to 2021 research.

If you did not get vaccinated against tetanus as an infant or child, you can still get it as an adult. If you have symptoms of tetanus, including muscle stiffness and spasms, you should go to the emergency room right away. Without treatment, tetanus can be fatal.

The best way to prevent an infection is to stop using heroin altogether. But if that’s not possible, you can take steps to reduce your risk:

  • Wash your hands thoroughly with soap and water before preparing your dose.
  • Use a new needle and syringe each time you inject heroin, and do not share drug injection equipment.
  • If you do share drug injection equipment, sterilize needles and syringes to reduce your risk of infection.
  • Learn more about needle exchange programs in your area.
  • Use a new, sterile filter or cotton every time you inject heroin.
  • Use sterile water to dissolve your drugs.
  • Clean your skin with rubbing alcohol before each injection.
  • Use condoms when you have anal or vaginal sex.
  • Get vaccinated for hepatitis B.
  • Get tested for viral infections such as HBV, HCV, and HIV.
  • Talk with your doctor about preventive treatments for HIV.
  • Seek emergency medical care if you have a fever, chills, nausea, vomiting, or other signs of an infection.

Support for substance use disorder

If you or someone you know is living with opioid use disorder involving heroin, you’re not alone.

There are resources available that can help. You can start by calling the Substance Abuse and Mental Health Services Administration’s National Helpline at 800-662-4357 for confidential, around-the-clock information about treatment and referrals.

SAMHSA also provides an online search engine to help you find a substance misuse treatment program in your area.

If you are in contact with a family doctor or another healthcare professional, like a social worker, they can also be a good source of information about treatment options.

People who inject heroin have an increased risk of contracting an infection.

Injections create a small puncture wound that bacteria and fungi can enter through. This allows them to spread through the body and infect your skin (cellulitis), heart (endocarditis), bones (osteomyelitis), or joints (septic arthritis).

In addition, sharing needles or other drug-injection equipment can put you at an increased risk of a viral infection like HBV, HCV, or HIV. If you use heroin, you might also experience other risk factors for infection, like certain sexual practices or a lack of housing.

You can take steps to prevent infection. But you should seek medical care as soon as possible if you’re experiencing symptoms.

To learn more about how to prevent complications of injection drug use, speak with a healthcare professional.