Intravenous drug use (recreational)
Editor-In-Chief: C. Michael Gibson, M.S., M.D. 
IV drug use is a relatively recent phenomenon arising from the invention of re-usable syringes and the synthesis of chemically pure morphine and cocaine. It was noted that administering drugs intravenously strengthened their effect.
There are a variety of reasons why drugs would be injected rather than taken through other methods.
- Increased effect — Injecting a drug intravenously means that more of the drug will reach the brain quicker. This also means that the drug will have a very strong and rapid onset (or rush).
- More efficient usage — Injection ensures that all of the drug will be absorbed.
- Bypasses the digestive system — Some people with sensitive stomachs find it very unpleasant to swallow drugs because of persistent cramps or nausea.
- Does not harm the lungs or mucous membranes — Unlike the many metres of surface veins, the mucous membranes occupy a more restricted surface area and can be permanently damaged by habitual insufflation (snorting).
In addition to general problems associated with IV drug use (see Intravenous therapy#Risks of intravenous therapy) there are some specific problems associated with the informal injection of drugs by non-professionals.
- Increased chance of blood-borne infection — This is generally a twofold problem. One is needle sharing which transmits blood-borne diseases between users and the other is secondary infection of injection sites caused by lack of hygiene and failure to rotate the injection site. In addition, the use of cotton to filter some drugs can lead to cotton fever.
- Increased chance of overdose — Because IV injection delivers a dose of drug straight into the bloodstream it bypasses the body's natural chemical defenses. Taking too much can result in unpleasant side effects or even death
- Scarring of the peripheral veins — This arises from the use of blunt injecting equipment. This is particularly common with users who have been injecting while in jail and re-use disposable syringes sometimes hundreds of times. IV drug use for an extended period may result in collapsed veins. Though rotating sites and allowing time to heal before reuse may decrease the likelyhood of this occuring, collapse of peripheral veins may still occur with prolonged IV drug use. IV drug users are among the most difficult patient populations to obtain blood-specimens from because of peripheral venous scarring.
- Increased chance of addiction — It is possible that the heightened effect of administering drugs intravenously can make the chances of addiction more likely but this is not established.
- Needle phobia — Quite a number of people have an intense aversion to needles which, in extreme cases, is called trypanophobia and can make them feel nauseous or faint.
- Social stigma — In many societies there is a social stigma attached to IV drug use. Many people feel that it is somehow "unclean" to take drugs in such a manner, even though they may be perfectly comfortable taking them by another route. It ,however, should be noted, that person taking all precautions will not subject themselves to diseases any more than a non-IV drug user. This may be because of its common use in inner cities and with lower-class people.
The drug, usually in a powder or crystal form (though not always), is dissolved in water, normally in a spoon. Users draw the required amount of water into a syringe and squirt this over the drugs. The solution is then mixed and heated from below if necessary. Heating is used mainly with heroin,(thought not always, depending on the type of heroin) but is also used when pharmaceutical drugs such Oxycontin or Dilaudid are injected to better separate the drug from the waxy filler; amphetamines lose potency when heated and cocaine HCl (powdered cocaine)dissolves quite easily. Heroin prepared for the European market usually requires the addition of a quantity of acidic mixer such as citric acid or ascorbic acid powder to dissolve the drug. Once the drugs are dissolved a small syringe, usually .5 or 1 cc, is used to draw the solution through a filter, usually cotton from a cigarette filter or cotton swab (cotton bud). The preferred injection site is the crook of the elbow (i.e., the Median Cephalic vein), on the user's non-writing hand. Other users opt to use the Basilic vein; While it may be easier to "hit", caution must be exercised as two nerves run parallel to the vein increasing the chance of nerve damage, as well as the chance of an arterial "nick".