How Crack Cocaine Works

Cocaine is a highly addictive substance. People who take it can become physically and psychologically dependant upon it to the point where they can't control their cravings. Researchers have found that subordinate cocaine-addicted monkeys will choose cocaine over food [source: Wake Forest University Baptist Medical Center].

Crack and other addictive drugs chemically alter a part of the brain called the reward system. As mentioned previously, when people smoke crack, the drug traps the chemical dopamine in the spaces between nerve cells. Dopamine creates the feelings of pleasure we get from enjoyable activities such as eating and having sex. But in crack users, dopamine keeps stimulating those cells, creating a "high" — a euphoric feeling that lasts about 15 minutes. But then the drug begins to wear off, leaving the person feeling let-down and depressed, resulting in a desire to smoke more crack in order to feel good again [source: Drug Policy Alliance].

The brain responds to the dopamine overload of the crack by shutting down some of its receptors. The result is that, after taking the drug for a while, crack users become less sensitive to it and find that they must take more and more of it to achieve the desired effect. Eventually, they cannot stop taking the drug because their brains have been "rewired" — they actually need it in order to function. How long does it take to become addicted? That varies from person to person, and an exact number is difficult to pin down, especially when physical addiction is paired with psychological addition [source: National Institute on Drug Abuse].

Of course, not everyone reacts the same way to extended use and not everyone who uses crack becomes addicted. Scientists believe dopamine acts in combination with other genetic and environmental influences to program some people's brains to become addicted to drugs. In fact, some users actually become more sensitive to crack as they take it. Some people die after taking a very small amount because of this increased sensitization.

When an addicted person stops taking crack, there is a "crash." He or she experiences the symptoms of withdrawal, including:

Various phases of cocaine and crack withdrawal last for months in heavy users. Emotional problems, poor sleep, lethargy and other problems afflict many people [source: Australian Department of Health].