Final answer:
Drug abuse is the improper use of drugs leading to dependence or toxicity and can result in drug addiction and tolerance, with increased risks of overdose and death.
Step-by-step explanation:
The improper use of common drugs that can lead to dependence or toxicity is best described as drug abuse. Drug abuse refers to the use of a drug without the advice of a medical professional and for reasons not originally intended. Continued abuse of psychoactive drugs can lead to drug addiction, which indicates a compulsive use of a substance despite negative consequences. Addiction often results in the development of tolerance, where the user needs increasing amounts of the drug to achieve the same effects, potentially leading to overdose and death. It is important to distinguish between drug abuse and terms like drug dependence and drug tolerance, as dependence can occur as a result of drug abuse and involves physical or psychological symptoms upon cessation of drug use. Tolerance specifically refers to a condition where increased doses of a drug are required to achieve effects once experienced at lower doses.