Drugs may be swallowed, smoked, inhaled through the nose as a powder (snorted), or injected. When drugs are injected, their effects may occur more quickly, be stronger, or both.
Drugs may be injected into a vein (intravenously), a muscle (intramuscularly), or under the skin (subcutaneously). Veins in the arms are typically used for intravenous injections, but if these areas become too scarred and damaged, drugs may be injected into veins anywhere in the body, including those of the thigh, neck, armpit or feet.
(See also Drug Use and Abuse.)
Injecting a drug has more risks than other methods. People are exposed not only to the effects of the drug but also to problems related to injection itself, such as the following:
Adulterants: Adulterants are substances that are added to a drug to alter its physical qualities. They are usually added, without the user’s knowledge, to reduce costs or to make the drug easier to use. Thus, users do not know what they are injecting. In street drugs such as heroin and cocaine, adulterants may also be added to enhance the drug's mind-altering properties or to substitute for the drug. Quinine, a common heroin adulterant, can cause heart abnormalities, visual problems, and deafness. Levamisole, a common cocaine adulterant, causes blood vessel inflammation and severe damage to the skin of the ears, nose, and face.
Fillers: Some people crush tablets of prescription drugs, dissolve them, and inject the solution intravenously. These people are injecting the fillers that tablets commonly contain (such as cellulose, talc, and cornstarch). Fillers can become trapped in the lungs, causing inflammation. Fillers can also damage heart valves, increasing the risk of infection there (endocarditis).
Bacteria and viruses: Injecting drugs with unsterilized needles, particularly needles used by someone else, can introduce bacteria and viruses into the body. As a result, abscesses may develop near the injection site, or bacteria or viruses may travel through the bloodstream to other parts of the body, such as the lungs, heart, brain, liver, or bones, and cause infection. Infection of the heart valves (endocarditis) is a common serious consequence of injecting drugs contaminated with bacteria or using dirty needles. Sharing needles can spread serious infections, such as hepatitis B and C and human immunodeficiency virus (HIV) infection.
Injuries due to needle use: Drug abuser’s elbow (myositis ossificans) is caused by repeated, inept needle punctures. The muscle around the elbow is replaced with scar tissue. Subcutaneous injections (those given under the skin, also called skin popping) can cause skin sores. Intravenous injections lead to scarring of veins (track marks), which makes the veins more and more difficult to inject and impairs blood flow.
Sometimes injection drug abuse is diagnosed when people go to a health care practitioner because they want help stopping use of the drug. Other people try to hide their drug use.
Practitioners may suspect problems with drug use when they notice changes in mood or behavior in a person. They may then do a thorough physical examination. Signs of drug abuse may be apparent. For example, repeatedly injecting drugs intravenously produces track marks. Track marks are lines of tiny, dark dots (needle punctures) surrounded by an area of darkened or discolored skin. Injecting drugs under the skin causes circular scars or ulcers. People who inject drugs may claim other reasons for the marks, such as frequent blood donations, bug bites, or other injuries.
Health care practitioners also use other methods (such as questionnaires) to identify abuse of some drugs and other substances and to determine the extent of drug use and its effects. Urine and sometimes blood tests may be done to check for the presence of drugs.
Specific treatment depends on the drug being used, but it typically involves counseling and sometimes involves use of other drugs. Family support and support groups help people remain committed to stopping use of the drug.
Treatment of complications is the same as that for similar complications with other causes. For example, abscesses may be drained, and antibiotics may be used to treat infections.
Because sharing needles is a common cause of HIV infection, a harm-reduction movement was started. Its purpose is to reduce the harm of drug use in users who cannot stop. Thus, users are provided clean needles and syringes so they do not reuse others’ needles. This strategy helps reduce the spread (and the cost to society) of HIV infection and hepatitis.