Drug dependence (addiction) is compulsive use of a substance despite negative consequences which can be severe; drug abuse is simply excessive use of a drug or use of a drug for purposes for which it was not medically intended.

Physical dependence on a substance (needing a drug to function) is not necessary or sufficient to define addiction. There are some substances which don't cause addiction but do cause physical dependence (for example, some blood pressure medications) and substances which cause addiction but not classic physical dependence (cocaine withdrawal, for example, doesn't have symptoms like vomiting and chills; it is mainly characterized by depression).

See also drug abuse and drug abuse first aid.

The exact cause of drug abuse and dependence is not known. However, the genetic make-up of the individual, the pharmacology of the particular drug, peer pressure, emotional distress, anxiety, depression, and environmental stress are all factors which seem to be involved.

Risk factors that predispose people to drug dependence are different from those which predispose to use or abuse. Peer pressure may lead to use or abuse, but at least half of those who go on to addiction have depression, attention-deficit disorder, post-traumatic stress disorder or another psychological problem.

Children who grow up in an environment of illicit drug use may first see their parents using drugs. This may put them at a higher risk for developing an addiction later in life for both environmental and genetic reasons.

Signs of drug use in children include but are not limited to:

• A change in the child's friends, a new group
• Seclusive behavior
• Long unexplained periods away from home
• Lying
• Stealing
• Involvement with the law
• Deteriorating family relations
• Obvious intoxication (e.g., drunk) , delirious, incoherent, or unconscious
• Distinct changes in behavior and normal attitude
• Decreased school performance

• Opiates and narcotics are powerful painkillers with sedative and euphoric qualities. These include heroin, opium, codeine, meperidine, (Demerol), hydromorphone (Dilaudid), Oxycontin and others.
• Central nervous systemstimulants include amphetamines, cocaine, dextroamphetamine, methamphetamine, and methylphenidate (Ritalin). The most commonly used stimulants are caffeine and nicotine. These drugs have a stimulating effect and can produce tolerance.
• Central nervous system depressants include barbiturates (amobarbital, pentobarbital, secobarbital), benzodiazepine (Valium, Ativan, Xanax), chloral hydrate, and paraldehyde. The most commonly used, by far, is alcohol. These substances produce a soothing sedative and anxiety-reducing effect and can lead to dependence.
• Hallucinogens include LSD, mescaline, psilocybin, and phencyclidine (PCP or "Angel Dust"). They have hallucinogenic properties and can produce psychological dependence.
• Tetrahydrocannabinol (THC) is the active ingredient found in cannabis, marijuana, and hashish. Although used for their relaxing properties, THC-derived drugs can also lead to paranoia and anxiety.

Drug intoxication and drug overdose may be accidental or intentional. Drug withdrawal symptoms can occur when use of a substance is stopped or reduced. Withdrawal symptoms vary, depending on the abused substance. The onset of withdrawal symptoms depends on the length of time the drug normally stays within the body. Drug intoxication, overdose, and withdrawal can be life-threatening in some situations.

Symptoms of use:

• needle marks on the skin in some cases (called "tracks")
• scars from skin abscesses
• rapid heart rate
• constricted pupils (pinpoint)
• relaxed and/or euphoric state ("nodding")
• coma, respiratory depression leading to coma and death in high doses

Symptoms of withdrawal:

• anxiety and difficulty sleeping
• sweating
• goose bumps (piloerection)
• runny nose (rhinorrhea)
• stomach cramps or diarrhea
• dilated pupils
• nausea and vomiting
• excessive sweating
• increase in blood pressure, pulse, and temperature

CENTRAL NERVOUS SYSTEMSTIMULANTS

Symptoms of cocaine use:

• euphoria (exaggerated feeling of well-being)
• dilated pupils
• rapid heart rate (tachycardia)
• restlessness and hyperactivity

Symptoms of cocaine withdrawal:

• fatigue and malaise
• depression
• vivid and unpleasant dreams

CENTRAL NERVOUS SYSTEM DEPRESSANTS

Symptoms of alcohol use:

• slurred speech
• lack of coordination
• decreased attention span
• impaired judgment

Symptoms of alcohol withdrawal:

• anxiety
• tremors
• seizures
• increase in blood pressure, pulse, and temperature
• delirium

HALLUCINOGENS

Symptoms of LSD use:

• anxiety
• frightening hallucinations
• paranoid delusions
• blurred vision
• dilated pupils
• tremor

Toxicology screens (drug testing) done on blood and urine specimens can reveal the presence of many chemicals and drugs in the body. The sensitivity depends upon the substance itself, when the substance was taken, and the testing laboratory. Blood tests are more likely to detect the presence of an abused substance than urine tests, however, urine drug screens are more frequently done.

Opiates and narcotics are usually present in the urine 12 to 36 hours after the last use, depending on the amount used and the frequency.

CNS stimulants such as cocaine can be detected in urine anywhere between 1 to 12 days, again depending in frequency of use.

CNS depressants such as Valium and Xanax are detected up to 7 days after the last day of use, mostly depending on the substance used and how quickly it is eliminated by the body (half-life).

Most hallucinogens are also detectable in the urine up to 7 days after the last use. However, cannabis can be detected up to 28 days in regular users.

Treatment for the person with drug abuse or dependence begins with the recognition of the problem. Though previously "denial" was considered a symptom of addiction, recent research has shown that this symptom can be dramatically reduced if addicts are treated with empathy and respect, rather than told what to do or "confronted."

Treatment of drug dependency involves detoxification, support and abstinence . Emergency treatment may be indicated for acute intoxication or drug overdose. Often, support of the respiratory system is needed as there may be a loss of consciousness. This usually entails being on a mechanical respirator temporarily. The specific treatment depends on the drug.

Detoxification is the gradual withdrawal of an abused substance in a controlled environment. Sometimes a drug with a similar action is substituted during the withdrawal process to reduce the unpleasant symptoms and risks associated with withdrawal. The process can be managed either on an inpatient or on an outpatient basis.

Rehabilitation is the process that occurs after detoxification and is often needed to prevent the relapse. Inpatient and outpatient programs are available. Individual, group, or family therapy is usually part of this process, which may continue for a month or longer. Information/support may also be sought from local 12 step groups (i.e., Alcoholics Anonymous (AA), Narcotics Anonymous (NA) which you can locate through your phone directory or online. See chemical dependence - support group. There are also alternative programs for those who do not like or do not do well in 12-step programs. These include SMART Recovery, Women For Sobriety and LifeRing Recovery which can also be found online.

If a depression or other mood disorder exists, it should be treated appropriately. In the past, addiction treatment providers discouraged use of antidepressant medications and this actually made relapse to addiction more likely. Very often drug abuse develops from efforts to self-treat mental illness.

Aftercare often involves life-long abstinence from drug abuse. Self-help groups such as Narcotics Anonymous can offer support. For heroin addicts, long-term methadone maintenance is the treatment with the best track record of cutting relapse, improving functioning and restoring health.

• depression
• relapse of drug abuse
• drug overdose
• bacterial endocarditis, hepatitis, thrombophlebitis, pulmonary emboli, malnutrition, or respiratory infections, caused by intravenousdrug abuse
• Infection with HIV through shared needles
• Disinhibition may lead to unsafe sexual practices which may result in unwanted pregnancies, sexually transmitted diseases, HIV or hepatitis.
• Problems with the law
• Increase in various cancer rates: lung and pharynx are associated with nicotine use, mouth and stomach cancer are associated with alcohol abuse and dependence for example.
• Problems with memory and concentration are seen with hallucinogen use, including marijuana (THC)