Because even though cocaine had a reputation for many years as a relatively harmless high, the fact is that the drug burns out the body and brain and can pose serious health risks to users. Smoking only compounds the risk, since crack carries all the dangers of regular cocaine , along with a few of its own. And right at the top of the list is the risk of overdose. And overdose is easy with crack, since it's absorbed so quickly at such high levels. And without immediate treatment, overdose can bring on convulsions, coma, and death.
Smoking crack can also cause respiratory problems and decreased lung function.
Heavy users report often congestion and coughing and pain in the lungs and throat after use. Other side effects include fatigue and malnutrition and possible liver damage. The drug also depletes levels of dopamine, a brain chemical involved in mood, attention, and motivation. Effects can be complicated by the simultaneous use of other drugs. Its physical risks are bad enough, but its addictiveness takes crack way over the top, trouble-wise.