Cocaine is the main active chemical in the leaves of Erythroxylon coca, a shrub which grows in South America and southeast Asia. The drug has significant physical and psychological effects.
The psychological effects mean that regular, high-dose users of cocaine develop bouts of uncontrolled and impulsive behaviour as well as impaired judgement. The initial attraction of the drug is the pleasant feelings of euphoria it induces, leading to a huge rush of energy and optimism. Increased self-esteem and sex drive are other immediate effects.
However, these mostly pleasant feelings diminish with successive doses. The cocaine-user needs progressively larger doses to achieve the same degree of euphoria; the high doses bring toxic side-effects, including paranoia and hallucinations. Regular users experience disordered thought patterns, by which they lose insight and may become violent.
But regular use can also destroy the body. When cocaine powder is snorted into the nostrils it causes blood vessels in the lining of the nasal passages to shrink. Repeated doses lead to a loss of blood supply to the septum - the wall dividing the nostrils. Eventually, this wall begins to disintegrate and a hole appears between the two nasal passages. A tell-tale sign of repeated cocaine use is a red, running, stuffed-up nose, due to a reflex widening of the blood vessels following initial constriction.
Once it gets into the body, cocaine releases large amounts of the stress hormone noradrenaline, which cause blood vessels to narrow. This leads to a sudden and significant rise in blood pressure, as well as a narrowing of the coronary arteries, putting users at risk of a heart attack or stroke. The blood vessels of a regular cocaine user aged 30 will resemble those of a 60-year-old.
The body's main blood vessel, the aorta, becomes damaged by long-term use of cocaine. A surge in blood pressure forces the blood between the inner and outer linings of the aorta. This false passage can burst (an aortic dissection), leading to a tearing pain in the chest or back. Research has found that more than one-third of patients with the potentially fatal condition had been using cocaine.
Cocaine and alcohol are synergistic; drinking makes the cocaine last longer because of the way the two drugs interact in the liver. Liver damage is more common when alcohol and cocaine are used together, and the risk of sudden death is 18 times greater than when cocaine is used on its own.
Other life-threatening effects associated with heavy use include brain seizures and kidney failure. Despite its sometimes benign reputation, cocaine can cause significant disability and death.