Legal prescription drugs are often taken in overdose to achieve effects other than the therapeutic effects for which they were intended.
Many street drugs have no therapeutic benefits.
Any use of them at all is a form of drug abuse . Often legitimate drugs are abused by people who take more than the recommended dose or take a medication with alcohol or another drug. Drug interactions also produce adverse effects. Therefore, it is important to let your physician know about all the drugs you are taking. Many drugs are addictive.