Injection Drug Use Clinical Presentation

Updated: Apr 19, 2022
  • Author: Hammad Khan, MD, MPH; Chief Editor: Glen L Xiong, MD  more...
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Obtain a complete history of the individual's past alcohol and drug use, including the following:

  • Age of onset for each drug used

  • Frequency of use

  • Quantities used

  • Progression of use with time

  • Medical and psychiatric symptoms associated with use

  • Routes of administration for each drug

  • Means of obtaining drugs or money for drugs

  • Longest periods of abstinence from drug use

  • History of prior chemical dependency treatments

Ask those who report injecting drug use which injecting sites they use, whether they use new or used needles, and whether they share other items used in the preparation of drugs for injection (eg, cookers, cotton). Ask those who share needles and syringes whether they attempt to clean the needles (eg, by using a bleach kit distributed by outreach workers).

Other risks associated with injecting drug use include contaminated drug solutions, buying ready-filled syringes, and sharing rinse water. "Backloading" is a practice in which a dealer transfers the drug solution from a larger syringe to a syringe provided by the user. "Flashblood" is a practice initially reported among sex workers in Dar es Salaam, in which an individual draws blood back into the syringe after having injected heroin, and then passes the syringe to another individual to inject the blood in the belief that this will prevent withdrawal symptoms.

Individuals may inject substances that are not supposed to be injected, such as pulverized (and unsterile) pills mixed with liquid. The liquid used to prepare drugs for injection is usually water, although use of lemonade and vinegar for this purpose has also been reported.

Ask about a history of prior systemic or local infections secondary to injecting drug use.



Begin with a standard physical assessment, paying special attention to signs of current injecting drug use, such as needle tracks. Other physical signs related to alcohol and drug use may also be present.

Common injection sites, such as the antecubital areas, should be inspected for evidence of recent injection. Some individuals may also use more unusual sites for injection, such as veins in the feet, hands, groin, and even the neck. As individuals who use injection drugs age and commonly used veins sclerose, these individuals may select progressively more dangerous sites. Hospitalized patients and patients who receive intravenous medication may inject drugs into their indwelling intravenous lines.

Check vital signs because changes are commonly associated with alcohol and drug intoxication and withdrawal, as well as with systemic infections secondary to injecting drug use. Stimulants, such as cocaine, may cause hyperthermia, an easily treatable yet easily overlooked condition. Persons who are intoxicated may also present with hypothermia, especially if they have been confused and wandering outside in cold weather.

Perform a mental status examination including the following considerations:

  • Pay special attention to level of alertness because many drug and alcohol intoxication and withdrawal states can produce changes in alertness and orientation.
  • Assess affect and mood and note whether suicidal ideation or intent is present. Drugs of abuse may cause or exacerbate depression and suicidal ideation.
  • Assess thought content and the presence or absence of hallucinations, delusions, or paranoid ideation and ask the patient whether these phenomena seem to be exacerbated or caused by drug use. Many patients with drug-induced delusions or hallucinations are in fact aware of the relationship between their drug use and the delusions or hallucinations.
  • Determine the presence or absence of homicidal or violent intent and ask whether the patient has guns at home.


The neurobiological mechanisms that underpin substance use disorders are thought to be complex and multifactorial including genetic predisposition and environmental stressors. At a neurocircuitry level, craving for addictive drugs is associated with increased activation of brain reward areas, including the nucleus accumbens and other brain areas. Drug use directly or indirectly elevates dopamine levels in the mesolimbic pathway of the brain, producing a pleasurable and positively reinforcing high.

Neuronal changes in specific brain regions (ie, neuroadaptation) occur in response to repeated drug use. Thus differences exist in the brains of addicted and nonaddicted individuals, and these differences can be demonstrated by brain imaging techniques.

Those who use drugs experience a compulsion to use the addictive drug regardless of negative consequences.

Those who use drugs may make the transition from noninjecting drug use to injecting drug use as their dependence on the drug becomes more severe. Injecting drug use is a popular route of drug administration because the injected substance has almost 100% bioavailability, and the onset of the drug high is fairly rapid, generally 15–30 seconds.

Those who use drugs use nonsterile injecting equipment largely because of the scarcity of sterile needles and syringes. Many people will use sterile needles and syringes if provided access to them. Making sterile injecting equipment available, either for purchase or via a needle exchange program, decreases rates of HIV and hepatitis B infections.



Local problems associated with injecting drug use include abscess, cellulitis, septic thrombophlebitis, local induration, necrotizing fascitis, gas gangrene, pyomyositis, mycotic aneurysm, compartmental syndromes, and foreign bodies (eg, broken needle parts) in local areas. The most common causative organisms reported are Staphylococcus aureus or Staphylococcus epidermidis, streptococci, and gram-negative bacilli.

Systemic problems associated with injecting drug use are HIV infection, hepatitis B or C, pneumonia or lung abscess from septic emboli to the lung, acute and subacute bacterial endocarditis, group A beta-hemolytic streptococcal septicemia, osteomyelitis, septic arthritis, candidal and other fungal infections, tetanus, clostridial myonecrosis, malaria, and amyloidosis. The endocarditis that occurs in individuals who inject drugs involves the right-sided heart valves; a recent review found no explanation for this predilection. [15]  A rare case of needle embolization to the lung has been reported.