Know what it does...

What are its short-term effects?
Short-term effects of cocaine/crack include constricted peripheral blood vessels, dilated pupils, increased temperature, heart rate, blood pressure, insomnia, loss of appetite, feelings of restlessness, irritability, and anxiety. Duration of cocaine's immediate euphoric effects, which include energy, reduced fatigue, and mental clarity, depends on how it is used. The faster the absorption, the more intense the high. However, the faster the absorption, the shorter the high lasts.The high from snorting may last 15 to 30 minutes, while that from smoking crack cocaine may last 5 to 10 minutes. Cocaine's effects are short lived, and once the drug leaves the brain, the user experiences a "coke crash" that includes depression, irritability, and fatigue.
What are its long-term effects?
High doses of cocaine and/or prolonged use can trigger paranoia. Smoking crack cocaine can produce a particularly aggressive paranoid behavior in users. When addicted individuals stop using cocaine, they often become depressed.