A drug addiction is the compulsive and continued use of a drug, or the loss of control over its use, despite the consequences. Drug dependence has both psychological and physical characteristics. If unable to obtain the drug, the person who is addicted may experience symptoms of distress or withdrawal and a need or craving to take the drug again. Signs of chemical dependency vary with the type of drug and the person abusing the drug. Some signs of chemical dependency include unpredictable behavior, such as being agitated one minute and lethargic the next.
Some addicted people have difficulty sleeping, while others sleep for long periods of time.
Those abusing drugs also often lose interest in eating, have dazed or expressionless eyes, flushed skin and a runny nose. Effects of drug abuse include memory loss, panic attacks, lung and brain damage, change in sex drive, decreased immunity to illness, heart problems, loss of interest in friends or family, depression, weight loss, paranoia, hallucinations, personality changes and increased risk for suicide or sudden death.