Injecting is the least common way of using drugs but also the most dangerous. Drugs that are injected are mainly of three kinds: opiates like heroin; sedatives and tranquillisers; and stimulants (amphetamines and cocaine). These may well be mixed to combine their different effects. For example, a mixture of heroin and cocaine is called a speedball.

In an EMCDDA report on a study where used syringes were analysed in 2022 (1,845 used analysed in total) from 10 EU cities plus Oslo, Odessa and Tunis, they found the drugs being injected in Europe are diverse with 54 different psychoactive substances identified. Heroin remained the most commonly found drug in the analysed syringes in six of the cities. Traces of stimulants (cocaine, synthetic cathinones, amphetamines) were found in a high proportion of syringes tested in all but one city (Vilnius) and cocaine was detected in over half of the syringes from Thessaloniki, Athens, Dublin and Cologne. The data also showed that a third of the syringes analysed contained residues of two or more drug categories, suggesting that people who use drugs often inject more than one substance or that syringes are re-used. The most frequent combination was a mix of a stimulant and an opioid.

Person injecting into their arm with a needle.


Any drug that is to be injected needs to be dissolved in a solution. Sterile water is the safest choice, however brown heroin is more easily dissolved in acids such as lemon juice or vinegar. The problem here is that both these substances may contain bacteria or become contaminated. Also, lemon juice has been associated with thrush and other fungal infections. Vitamin C is thought to be the safest acid to use, though it still has dangers.

When injected into a vein, the drug enters the blood stream and some is carried directly to the brain, producing a noticeable effect within seconds. For these reasons the onset of the drug’s effects (the ‘rush’) is quicker and more striking after injection. Drugs like heroin or cocaine, that have been prepared for injecting, are usually injected directly into the vein. Other drugs such as anabolic steroids are injected under the skin or into muscles.

The major dangers of injecting are overdose; infection from non-sterile injection methods (including hepatitis, AIDS and other diseases transmitted by more than one injector sharing the same needle); abscesses and gangrene caused by missing the vein when injecting; and damage from using crushed-up tablets and other formulations not meant to be injected.

For some people the ritual of injection may become as important as the effect of the drug, and if no drugs are available almost anything will be injected including warm water.

Harm reduction

While injecting is the most dangerous mode of administration there are steps that can be taken to reduce its risks. It is important to keep equipment as sterile as possible and to avoid sharing. If needles are shared then it is safer to use low dead space versions. These syringes have less space between the needle and the plunger after injecting which means that less blood and drug remain here and so there is less risk of spreading blood-borne viruses, such as HIV and hepatitis B and C.

This animation explains more: Low Dead Space Needles and Syringes.

The Exchange Supplies site provides equipment such as low dead space syringes, sterile citric acid for dissolving drugs, and foil. The site also has a large resource of booklets and posters on how to inject more safely, including, a guide to safer Injecting called the Safer Injecting Handbook

Needle exchanges

Many pharmacies and drug services offer a needle exchange where you can get free, sterile injecting equipment such as needles, spoons, citric acid, filters and foil. You will also be given a free container to dispose of used needles in, which you can take back to the service. Some hostels also provide this service. In fact, wherever you see the sign below, there is a needle exchange operating.

You do not need to make an appointment to visit a service and you will be able to speak to someone in a private room if you wish. You do not have to give your full name and anything you do tell the service is confidential.

Often, at a needle exchange you can get advice on how to inject more safely and what to do in the event of an overdose. A free Naloxone kit on reversing opiate overdoses, i.e. overdoses from drugs like heroin, morphine and methadone is available too and you will be trained in how to use it.

It is also possible to be tested for blood borne viruses such as HIV, hep B and hep C. and to be vaccinated against hep B.

In September 2021, the charity Humankind, developed a set of Minimum Standards for Needle Exchanges and Harm Reduction Services. These standards aim to improve coverage, reduce the risk of needle finds, and ensure consistent high-quality delivery of needle exchange programmes. NICE has also published public health guidelines for needle exchange programmes.

Updated October 2023

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