Drug addiction is a disease that changes the structure and function of the brain caused by prolonged drug abuse. Drug addiction can start through using pain relievers long-term under doctor's advice, taking drugs to stay awake for exams, family history of drug use, or using drugs to cope with frustration and depression. Signs of drug addiction include spending a lot of time alone, losing interest in hobbies, nervousness, irregular sleep patterns, and work problems. To avoid addiction, one should undergo health evaluations, participate in counseling, join aftercare programs, engage in therapies, increase awareness of drugs, curb the drug trade, and enforce strict rules.