• Cannabis compounds. Contained in marijuana and hashish.
• Central nervous system depressants. Barbiturates and benzodiazepines. Benzodiazepines include tranquilizers such as diazepam (Valium), alprazolam (Xanax), oxazepam (Serax), lorazepam (Ativan), clonazepam (Klonopin) and chlordiazepoxide (Librium).
• Central nervous system stimulants. Amphetamines, methamphetamine, cocaine and methylphenidate (Ritalin).
• Designer drugs. Synthetic compounds such as Ecstasy, which has both amphetamine-like and hallucinogenic effects.
• Hallucinogens. LSD, phencyclidine (PCP) and ketamine (special K).
• Inhalants. Glue, paint, solvents and nitrous oxide.
• Opioids. Narcotic, painkilling drugs produced naturally from opium or made synthetically. They include heroin, morphine, codeine, methadone and oxycodone (Oxycontin).

• Feeling that you need the drug regularly (sometimes many times a day)
• Making certain that you maintain a supply of the drug
• Failing in your attempts to stop using the drug
• Doing things that are normally out of character (like stealing) to obtain the drug.
• Feeling that you need the drug to deal with your problems

• A sense of relaxation
• A heightening of the senses (vision, hearing and taste)
• Memory loss
• Increased blood pressure
• Increased heart rate
• Bloodshot eyes
• Poor coordination
• Difficulty concentrating
• Poor judgment
• Paranoia

• Slurred speech
• Poor coordination
• Memory loss
• Confusion
• Slowed heart rate
• Dizziness
• Inappropriate display of emotions
• Drowsiness or coma

• Euphoria
• Decreased appetite
• Rapid speech
• Irritability
• Restlessness
• Depression as the drug wears off

Signs and symptoms of LSD use include:

• Hallucinations
• Greatly impaired perception of reality
• Rapid heart rate
• High blood pressure
• Tremors
• Flashbacks (reliving hallucinations — even years later)

Signs and symptoms of PCP use include:

• Hallucinations
• Euphoria
• Delusions
• Sweating and flushing
• Disorientation
• Poor coordination
• Paranoia
• Drooling, nausea or vomiting
• Suicidal thoughts

Signs and symptoms of ketamine use include:

• Increased heart rate
• Nausea and vomiting
• Numbness
• Impaired motor function

• Sedation
• Depression
• Confusion
• Constipation
• Slowed breathing
• Needle marks (if injecting drugs)

• School performance. Your child suddenly shows an active dislike of school and looks for excuses to stay home. Check your child's attendance record with the school, and look for a sudden and unexplained drop in performance.
• Physical health. Listlessness and apathy may indicate your child is using certain drugs.
• Appearance. A sudden lack of interest in general appearance may be a warning sign of drug use.
• Personal behavior. Exaggerated efforts to bar you from entering their room or knowing where they go with their friends might indicate drug use.
• Money. Unreasonable requests for money may be a sign of drug use. You may also discover that money is missing from previously safe places at home. Items may disappear from your home because they're being sold to support a drug habit.

• Central nervous system depressants. Minor side effects of withdrawal may include restlessness, anxiety, sleep problems and sweating. More serious signs and symptoms might also include hallucinations, whole-body tremors, seizures, dehydration and weakness. The most serious stage of withdrawal may include delirium and is potentially life-threatening. Withdrawal therapy may involve your gradually scaling back the amount of the drug.
   
• Central nervous system stimulants. Side effects of withdrawal typically include depression, fatigue, anxiety and intense cravings. In some cases, signs and symptoms might include suicide attempts, paranoia and impaired contact with reality (acute psychosis). Treatment during withdrawal is usually limited to emotional support from your family, friends and doctor. Your doctor may recommend medications to treat paranoid psychosis or depression.
   
• Opioids. Side effects of withdrawal of opioids such as heroin, morphine, oxycodone or codeine can range from something as minor as a runny nose, perspiration, yawning, feeling anxiety and craving the drug through to sleeplessness, depression, dilated pupils, rapid pulse, rapid breathing, high blood pressure, abdominal cramps, tremors, bone and muscle pain, vomiting, and diarrhea. Doctors may substitute a synthetic opiate, such as methadone, to reduce the craving for heroin and to gently ease people away from heroin. The most recently approved medication to ease withdrawal from opiates is buprenorphine (Suboxone, Subutex), which can be prescribed by a doctor rather than a treatment center.

• Counseling. Individual or family counseling with a psychologist, psychiatrist or addiction counselor may help you resist the temptation to resume using addictive drugs.
   
• Treatment programs. Treatment programs generally include educational sessions and individual, group and family counseling. They're available in various settings from outpatient to residential and inpatient programs.
   
• Self-help groups. These groups tend to use the 12-step model first developed by Alcoholics Anonymous. Self-help groups, such as Narcotics Anonymous, exist for people addicted to drugs such as cocaine, sedatives and narcotics. The message is that addiction is a chronic disorder with a danger of relapse and that ongoing maintenance treatment is necessary to prevent a relapse.