Drug abuse

Some cases of severe delirium, hallucinations, and violence have also been reported. Such cases should raise suspicion that the marijuana may have been laced with another agent such as PCP.

Marijuana has specific effects that may decrease one's ability to perform tasks requiring a great deal of coordination (such as driving a car). Visual tracking is impaired and the sense of time is typically prolonged.

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Learning may be greatly affected because the drug diminishes one's ability to concentrate and pay attention. Studies have shown that learning may become "state-dependent" meaning that information acquired or learned while under the influence of marijuana is best recalled in the same state of drug influence.

Other marijuana effects may include blood-shot eyes; increased heart rate and blood pressure; bronchodilatation, or in some users, bronchial irritation leading to bronchoconstriction and/or bronchospasm; pharyngitis, sinusitis, bronchitis, and asthma in heavy users; possible detrimental effects upon the immune system.

Regular users, upon stopping marijuana use, may experience withdrawal effects. These may include agitation, insomnia, irritability, and anxiety. Because the metabolite (the substance formed when the body breaks down the drug) of marijuana may be stored in the body's fat tissue, evidence of marijuana may be demonstrated in heavy users through urine testing up to 1 month after discontinuing the drug.

The active component in cannabis is believed to have medical properties. Many maintain that it is effective in the treatment of nausea caused by chemotherapy in cancer patients.

Others claim that cannabis stimulates appetite in patients with AIDS or is useful in the treatment of glaucoma. While the active ingredient in marijuana has been approved as a synthetic medication by the FDA (dronabinol) for these purposes, use of whole marijuana remains hugely controversial. Currently, cannabis is illegal even for medical use under federal law.

PHENCYCLIDINE (PCP, "angel dust")

It is difficult to estimate the current use of phencyclidine in the United States because many individuals do not recognize that they have taken it. Other illicit substances (such as marijuana) can be laced with PCP without the user being aware of it.

A 1986 National Institute of Drug Abuse survey of high school seniors revealed that over 12% of the students had used hallucinogens and that many of these drugs probably contained PCP.

PCP use in the U.S. dates back to 1967 when it was sold as the "Peace Pill" in the Haight-Ashbury district of San Francisco. Its use never became very popular because it had a reputation for causing "bad trips."