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Drug abuse

Drug abuse is the recurrent use of illegal drugs, or the misuse of prescription or over-the-counter drugs with negative consequences. These consequences may involve

  • Problems at work, school, home or in interpersonal relationships
  • Problems with the law
  • Physical risks that come with using drugs in dangerous situations

Alternative Names

Substance abuse; Illicit drug abuse; Narcotic abuse; Hallucinogen abuse



Marijuana is also called "grass," "pot," "reefer," "joint," "hashish," "cannabis," "weed," and "Mary Jane."

About 2 in 5 Americans have used marijuana at least once in their life.

Marijuana comes from a plant called hemp (Cannabis sativa). The main, active ingredient in marijuana is THC (short for delta-9-tetrahydrocannabinol). This and other ingredients, called cannabinoids, are found in the leaves and flowering parts of the marijuana plant. Hashish is a substance taken from the tops of female marijuana plants. It contains the highest amount of THC.

How fast you feel the effects of marijuana depend on how you use it:

  • If you breathe in marijuana smoke (such as from a joint or pipe), you may feel the effects within seconds to several minutes.
  • If you eat foods containing the drug (such as "hash brownies,") you may feel the effects within 30 - 60 minutes.

Marijuana acts on your central nervous system. Low to moderate amounts of the drug may cause:

  • Increased appetite ("the munchies")
  • Feeling of joy (euphoria)
  • Relaxed feeling
  • Increased sensations of sight, hearing, and taste

Other effects can include:

  • Feelings of panic
  • Anxiety
  • Excessive fear (paranoia)
  • Decreased ability to perform tasks that require coordination (such as driving a car)
  • Decreased interest in completing tasks
  • Firmly held false beliefs (delusions)
  • Seeing or hearing things that aren't there (hallucinations)
  • Bloodshot eyes
  • Increased heart rate and blood pressure
  • Infections such as sinusitis , bronchitis , and asthma in heavy users
  • Irritation of the airways causing narrowing or spasms
  • Possibly weakening of the immune system
  • Sore throat
  • Trouble concentrating and paying attention, which can interfere with learning
  • Trouble telling oneself from others
  • Violence (may be related to marijuana that is laced with a drug called PCP)

Regular users may have withdrawal effects when they stop marijuana use. These may include:


The medical use of marijuana is controversial, yet it's active ingredient (THC) is legal for medical purposes in at least 16 states. (Whole marijuana is illegal, even for medical use.)

THC has been approved by the U.S. Food and Drug Administration (FDA) for the following medical purposes:

  • Relieving chronic pain and spasticity
  • Stimulating appetite in patients with AIDS or who have undergone chemotherapy
  • Treating glaucoma
  • Treating nausea caused by chemotherapy in cancer patients

PHENCYCLIDINE (PCP, "angel dust")

PCP is an illegal drug that comes as a white powder, which can be dissolved in alcohol or water. PCP may be smoked, shot into a vein, or taken by mouth. How quickly it affects you depends on how you take it.

  • Shooting up: If given through a vein, PCP's effects start within 2-5 minutes.
  • Smoked: The effects begin within 2 - 5 minutes, peaking at 15 - 30 minutes.
  • Taken by mouth: In pill form, or mixed with food or drinks, PCP's effects usually start within 30 minutes. The effects tend to peak in about 2 - 5 hours.

Different doses of PCP may cause different effects:

  • Lower doses of PCP typically produce feelings of joy (euphoria) and less inhibition, similar to being drunk.
  • Higher doses can cause numbness throughout the body, and perception changes that may lead to extreme anxiety and violence.
  • Large doses may produce paranoia, "hearing voices" (auditory hallucinations), and other forms of psychosis , similar to schizophrenia .
  • Massive doses, usually from taking the drug by mouth, may cause kidney failure , heart arrhythmias , muscle rigidity , seizures , and even death.

Because of the pain-killing (analgesic ) properties of PCP, users who get seriously injured may not feel any pain.


LSD (lysergic acid diethylamide) is a strong hallucinogen. Only tiny amounts are needed to cause effects, such as hallucinations.

LSD use may cause:

  • Anxiety
  • Blurred vision
  • Dilated pupils
  • Seeing things that aren't there (hallucinations )
  • Paranoia and other delusions
  • Tremors

Other commonly abused hallucinogens include:

  • Psilocybin (mushrooms, "’shrooms")
  • Peyote (a cactus plant containing the active ingredient mescaline)

Hallucinogens can lead to extreme anxiety and loss of touch with reality, called "bad trips". These experiences can come back as a "flashback," even without using the drug again. Such experiences typically occur during times of increased stress, and tend to occur less often and intensely after stopping the drugs.


Cocaine is a strong stimulant. The abuse of cocaine increased dramatically in the late 1980s and early 1990s, but is now on the decline. Other names to describe different forms of cocaine include "crack," "coke," "snow," and "speedball."

Cocaine may be taken in different ways:

  • Snorting: Inhaling it through the nose
  • Shooting up: Dissolving it in water and injecting it into a vein
  • Speedball: Mixing with heroin and injecting into a vein
  • Smoked: Cocaine may be changed into smokeable forms known as freebase or crack

Smoking cocaine typically produces a nearly instant and intense sense of joy (euphoria). Other effects include:

  • Feelings of increased confidence and energy
  • Less inhibition
  • Local numbness

Regular users of cocaine may need larger amounts of the drug to feel these effects. Regular users of cocaine may develop:

  • Loss of interest in school, work, family, and friends
  • Memory loss
  • Mood swings
  • Sleep problems
  • Social withdrawal
  • Heart disease and other blood vessel disease
  • A hole in the septum that separates the nostrils

Heavy use may cause paranoia, which can lead to violence.


Amphetamines are stimulants. Other names used to describe amphetamines or methamphetamines include "crystal," "go," "crank," and "cross-tops."

Amphetamines can be very addictive. Prescription amphetamines are considered controlled substances. Over-the-counter (OTC) amphetamine look-alike drugs are often abused. These drugs typically contain caffeine and other stimulants, and are sold as appetite suppressants or stay-awake/stay-alert aids.

Signs and symptoms of stimulant use include:

  • Dilated pupils
  • Exaggerated feeling of well-being (euphoria)
  • Fast heart rate
  • Restlessness and hyperactivity
  • Skin flushing
  • Sleep disturbances
  • Tremors
  • Appetite decrease and weight loss


Inhalant use became popular with young teens in the 1960s with "glue sniffing." Since then, a greater variety of inhalants have become popular. Inhalant use typically involves younger teens or school-age children.

Commonly abused inhalants include:

  • Aerosols for deodorants or hair sprays
  • Cleaning fluids
  • Gasoline
  • Liquid typewriter correction fluid
  • Model glue
  • Spray paints

Negative effects of inhalant abuse include:


Opiates come from opium poppies. These drugs include morphine and codeine. Opioids are artificial substances that have the same effect as morphine or codeine. The term "narcotic" refers to either type of drug.

Narcotics are powerful painkillers that cause drowsiness (sedation) and, sometimes, feelings of euphoria.

These drugs include:

  • Codeine
  • Heroin
  • Hydromorphone (Dilaudid)
  • Methadone
  • Meperidine (Demerol)
  • Opium
  • Oxycodone (Percocet or Oxycontin)

Signs and symptoms of narcotic use include:

  • Sedation
  • Needle marks on the skin ("tracks"), scars or abscesses  if drug use is by injection
  • Relaxed or euphoric state
  • Small "pinpoint" pupils
  • Coma, respiratory depression, and death in high doses

Because heroin is commonly injected into a vein (used intravenously), there are health concerns about sharing contaminated needles among IV drug users. Complications of sharing contaminated needles include hepatitis , HIV infection, and AIDS .


These substances produce sedating and anxiety-reducing effects, which may be therapeutic in some cases and lead to abuse or dependence in others.

These types of drugs include:

  • Alcohol
  • Barbiturates (e.g. amobarbital, pentobarbital, secobarbital), also called "yellow jackets"
  • Benzodiazepines (e.g. Valium, Ativan, Xanax)
  • Chloral hydrate
  • Paraldehyde

Signs and symptoms of excessive alcohol or other depressant use include:

  • Decreased attention span
  • Impaired judgment
  • Lack of coordination
  • Slurred speech


A number of other illegal drugs have become popular and available in recent years, including:

  • Ketamine, a substance related to PCP, commonly called "Special K"
  • "Ecstasy," or MDMA (3,4-methylenedioxy-methamphetamine)
  • GHB and Rohypnol, also called "date rape," "acquaintance rape," or "drug-assisted assault" drugs


  • If you are concerned about the possibility of getting addicted to any prescribed medications
  • If you are concerned about possible drug abuse by you or a family member
  • If you are interested in getting more information on drug abuse
  • If you are seeking treatment of drug abuse for yourself or a family member


There are a number of different support groups available to help those with drug abuse. They include:

  • Al-anon/Alateen
  • Alcoholics Anonymous (AA)
  • Narcotics Anonymous (NA)
  • Marijuana Anonymous (MA)
  • LifeRing Recovery
  • Moderation Management
  • SMART Recovery


Samet JH. Drug abuse and dependence. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier;2007:chap 32.

Updated: 2/8/2013

David B. Merrill, MD, Assistant Clinical Professor of Psychiatry, Department of Psychiatry, Columbia University Medical Center, New York, NY. Also reviewed by David Zieve, MD, MHA, Bethanne Black, and the A.D.A.M. Editorial team.

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