Substance abuse can have different symptoms in different people. “Drug abuse” is not used in the DSM or ICD. In the DSM, the term “substance abuse” is used instead to mean the misuse of one of ten different types of drugs.  A person can also become dependent on drugs. Repetitive use of a drug can cause dependence as well as tolerance. Tolerance happens when it takes more of a drug to produce the same effect than a previous time.