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Safe and Drug-Free Schools: Alcohol, Tobacco, and Other Drugs
Facts about alcohol, tobacco, and other drugs / Matrix of commonly abused drugs


Marijuana is made from the dried and crushed leaves and flowers of the plant cannabis sativa, marijuana is a combination of mind-altering ingredients called cannabinoids. The amount of THC (delta-9-tetrahydrocannabinol), the chief active ingredient in marijuana, determines how strong its effects will be. Usually smoked as a cigarette or joint, or in a pipe or bong, marijuana has appeared in "blunts" in recent years. These are cigars that have been emptied of tobacco and re-filled with marijuana, sometimes in combination with another drug, such as crack. Some users also mix marijuana into foods or use it to brew tea. Today's marijuana is as much as 10 times stronger than the marijuana used in the early 1970's.

Marijuana use reduces white cell production, which lowers the body's ability to fight infection and disease. Heavy cannabis users have higher rates of illness such as flu, colds, and infections. Marijuana accumulates in your body and THC can remain in the tissues of the body for days or weeks. Frequent users may never be rid of the drug, and the long-term health effects of this accumulation are unknown. Marijuana smoke contains more cancer-causing agents than tobacco smoke. Researchers report that marijuana cigarettes release five times as much carbon monoxide into the bloodstream and three times as much tar into the lungs of smokers as tobacco cigarettes.

Researchers have found that smoking marijuana leads to some changes in the brain similar to those caused by cocaine, heroin and alcohol. Cannabinoids remain in the fat cells of the bodies of marijuana users. Since one-third of the brain is fat, cannabinoids are stored in the brain. Marijuana can hinder learning by impairing thinking, reading comprehension and verbal and math skills. It can impair or reduce short-term memory, alter sense of time, and reduce concentration. Marijuana affects reasoning and judgment. Using this drug affects a young person's opportunity to learn, to feel, to develop relationships, and to discover who he or she is. Youth who use marijuana have:

  • Low energy

  • Lack of ambition

  • Lack of interest in school activities

  • Short-term memory -kids may be labeled "slow learners", when in fact their memory is affect by the drug.

  • Low achievement -frequent users tend to have lower grades than nonusers


There are some signs you may be able to see if someone is using marijuana. He or she might:

  • Seem dizzy and have trouble walking

  • Seem silly and giggly for no reason

  • Have very red, bloodshot eyes

  • Have a hard time remembering things that just happened

  • Have a distorted sense of time passage -tendency to overestimate time intervals

  • Have an odor similar to burnt rope on clothing or breath

  • Have brown residue on fingers

  • Use or possess paraphernalia including roach clips, packs of rolling papers, pipes or bongs.

Marijuana users are difficult to recognize unless they are under the influence of the drug at the time of observation. Casual users may show none of the general symptoms. Marijuana does have a distinct odor and may be the same color or a bit greener than tobacco.

Prevalence of Use

The following sites can provide you with additional information on marijuana.

The National Institute on Drug Abuse (NIDA) has general information on marijuana and the "Mind Over Matter" series designed to encourage young people in grades 5 thru 9 to learn about the effects of drug abuse on the body and the brain.

Marijuana: Facts Parents Need to Know is a booklet produced by the National Institute on Drug Abuse.

The National Clearinghouse for Alcohol and Drug Information's home page has information on steroids and other substances of abuse.

Substance Abuse & Mental Health Services Administration's (SAMHSA) Office of Applied Studies (OAS) provides the latest national data on alcohol, tobacco, marijuana and other drug abuse. 

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