Most people die from heroin overdoses when their bodies forget to breathe.

Heroin is most often mixed with water and injected. Injecting it minimizes the lag time between when the drug is taken and effects are felt -- with injection, the effects are almost immediate.

It can also be smoked, snorted or eaten, but smoking or eating destroys some of the drug and mutes its effects.

When someone takes heroin there is an immediate rush. Then the body feels an extreme form of relaxation and a decreased sense of pain.

What's happening inside the body is the heroin is turning into morphine. Morphine has a chemical structure similar to endorphins -- the chemicals your brain makes when you feel stressed out or are in pain. Endorphins inhibit your neurons from firing, so they halt pain and create a good feeling.

[link to www.cnn.com]