Perhaps the most dangerous aspect of crack usage is the high risk of overdose. Since crack is more potent than street cocaine, it enters the bloodstream more quickly and in higher concentrations. This is particularly risky since smoking the drug makes it difficult to estimate dosage. The most frequent overdose that people experience when smoking crack cocaine is on the mild side and is felt as very rapid heart beat and hyperventilation. These reactions are often accompanied by a feeling of impending death. Although most people survive, several thousand are killed by overdosing on crack every year. All forms of cocaine and crack cocaine use have been linked with heart failure in users, even healthy users.

Crack is made from cocaine in a process called freebasing, in which cocaine powder is cooked with ammonia or sodium bicarbonate (baking soda) to create rocks, chips, or chunks that can be smoked. The term crack refers to the crackling sound that is heard when the mixture is smoked. Crack is usually smoked in a pipe. Because it's smoked, crack cocaine effects are felt more quickly and they are more intense than those of powder cocaine. However, the effects of smoked crack are shorter lived than the effects of snorted powder cocaine.