Alcohol, nicotine or caffeine may also be abused. Anabolic steroids and human growth hormone may be abused by athletes and body builders. Prescription drugs can be abused, if taken in ways they are not directed to be taken.
Some drugs are addictive.
This means one can become physically dependent upon them. Withdrawal symptoms will occur in the absence of the drug. Some examples of addictive drugs are heroin, crack and Librium. Other drugs are psychologically habituating. This means that one can become psychologically dependent.