Cause

Most of the time, drug abuse starts with casual use. People don't use drugs because they want to be addicted. Drugs can make you feel good for a while. They may make you feel energetic, self-confident, and powerful. You may take a drug to reduce stress or anxiety or to help you forget a problem.

Drug use changes your brain and how it works. If you continue to use drugs, you may develop strong cravings for them, and it may get harder to say "no" to further use. At the same time, you may begin to lose interest in activities you always enjoyed. This is because you may feel that they are not as enjoyable as using drugs. You may then become dependent.

Not everyone who uses drugs abuses them or becomes dependent. Other things that influence whether this happens include your genes, family, friends, and life situations. For more information, see What Happens and What Increases Your Risk.

Symptoms

When drug use, abuse, and dependence occur, you are more likely to have changes in your behavior than to have physical symptoms.

Changes in behavior

• Changes in sleeping or eating habits, less attention to dressing and grooming, or less interest in sex.
• Up-and-down moods, a mood or attitude that is getting worse, or not caring about the future.
• Anger toward others, or treating others badly.
• Sneaky behavior, lying, or stealing.
• Poor family relationships, or relationships that are getting worse.
• New problems at work or school, or problems with the law.
• Not keeping up with old friends and activities, and finding new friends and not wanting old friends to meet them.

These signs don't always mean a person is using drugs. The behavior could be because of work or school stress, or it could be a sign of depression or another medical problem. But behavior changes like these are common in people who abuse drugs.

If you think you or a loved one might have a drug problem, use this short quiz to check your drug use:

Assess Your Drug Use(What is a PDF document?)

Physical signs of drug abuse or dependence

• Red eyes, a sore throat, and a dry cough.
• Needle marks on the arm or other area of the body.
• Small, "pinpoint" pupils in the eyes.
• Losing weight without trying to, or not feeling like eating.
• Changes in how well you sleep.
• Seeing things that don't exist (hallucinations).

Symptoms in older adults

Drug abuse in older adults may go unnoticed, since the signs may be similar to those of aging. Older adults often take more medicines, such as sleep medicines and painkillers, that can lead to dependence.

Symptoms of withdrawal

When you are dependent on a drug and you stop using it, you may have physical symptoms known as withdrawal. These symptoms differ for each drug. They can include feeling sick to your stomach, vomiting, having belly pain, sweats, nervousness and shaking, and seizures.