Those who abuse drugs may suffer many physical and psychological problems as a consequence of their behaviour. Some problems can be directly related to the pharmacological effects of the drugs, but many are associated with the methods of drug administration and more specifically with self-injection. Some drug abusers inject subcutaneously (‘skin-popping’) and some do so intramuscularly, but the most favoured route is intravenous – because this delivers the whole dose, with no wastage, directly into the bloodstream, producing the maximum effect with minimum delay, although increasing the likelihood of a toxic overdose. Whatever complications ensue, their management and the ultimate prognosis is adversely affected by the poor general state of health of many of those who are severely dependent on drugs, resulting from poor social conditions, malnutrition and self-neglect.

No attempt has been made in this chapter to cover all the possible complications of drug abuse, but to address instead those situations that are most frequent and cause particular problems. The emphasis throughout is on the practical aspects of diagnosis and patient-management.

Infective complications of injection

Whatever route is chosen, injection carries a high risk of infection. Needles and syringes are often used several times and may be shared with others. Sterilization of injection equipment, if it is attempted at all, is usually inadequate and therefore ineffective, and the skin is rarely cleaned before injection takes place. Dirty injection habits cause local infection at the site where the needle penetrates the skin and the underlying vein and more generalized illnesses, which may be of life-threatening severity. Some infections, notably hepatitis and HIV, are transmitted directly from one drug abuser to another as infected blood contaminates shared syringes and needles and other injecting paraphernalia.