Crack is a very addictive drug. People can get both physically and psychologically addicted to crack (meaning that the body and the mind can both become addicted to, or "hooked on," the drug.) Using crack is dangerous for many reasons. The drug can cause physical problems (like heart and lung problems or rotted teeth) and psychological (or mental) problems, like depression and psychosis (not understanding what is real and what is not real). An overdose of crack - taking too much of the drug - can cause death. Also, because crack is illegal, people have to break the law in order to get it, and they can get sent to jail if they are caught. People may also do other illegal things in order to get crack or to get money to buy crack, because the urge to get the drug is so strong in people who are addicted.