Injection leads to a quicker, more powerful high, but sharing needles can increase the risk of infection. Users often experience a feeling of well-being, contentment and detachment from daily worries. Tolerance builds up with use so greater amounts of the drug are needed to create the high. This can eventually lead to addiction. It also increases the risk of overdosing.
Research shows that overdose often occurs after users have tried to come off the drug.
When they start taking it again, they often resort to the dose they were on when they stopped, although their tolerance is not as high. The fact that heroin is often adulterated with other substances can also cause overdose. Symptoms of an overdose include rapid heartbeat, heart failure, shortness of breath, unconsciousness and coma. When unconscious, the user is at risk of choking on their own vomit. Heroin can also cause unexplained sudden death due to the user having a particular reaction to the drug, to injecting heroin and to impurities present in the drug.