About 2 in 5 Americans have used marijuana (also called “grass,” “pot,” “reefer,” “joint,” “hashish,” “cannabis,” “weed,” and “Mary Jane”) at least once. Approximately 10% of the population uses it on a regular basis. Next to tobacco, and alcohol in some areas, marijuana is the most popular substance young people use regularly.
The source of marijuana is the hemp plant (cannabis sativa). The active ingredients are THC (delta-9-tetrahydrocannabinol) and other cannabinoids, which are found in the leaves and flowering shoots of the plant.
Hashish is a resinous substance, taken from the tops of female plants. It contains the highest concentration of THC.
The drug dose delivered from any particular preparation of marijuana varies greatly. The concentration of THC may vary as much as a hundred fold, due to diluting or contaminating materials.
The effects of marijuana may be felt from seconds to several minutes after inhaling the smoke (from a joint or a pipe), or within 30 – 60 minutes after ingestion (eating foods containing marijuana, such as “hash brownies”).
Because the effects are felt almost immediately by the smoker, further inhalation can be stopped at any time to regulate the effect. In contrast, those eating marijuana experience effects that are slower to develop, cumulative (they add up), longer-lasting, and more variable, making unpleasant reactions more likely.
The primary effects of marijuana are behavioral, because the drug affects the central nervous system (CNS). Popular use of marijuana started because of its effects of euphoria (feeling of joy), relaxation, and increased visual, auditory (hearing), and taste perceptions that may occur with low-to-moderate doses. Most users also report an increase in their appetite (“the munchies”).
Unpleasant effects that may occur include depersonalization (inability to distinguish oneself from others), changed body image, disorientation, and acute panic reactions or severe paranoia.
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.
Learning may be greatly affected because the drug reduces 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 (widening of the airways)
- In some users, bronchial (airway) irritation leading to bronchoconstriction (narrowing of the airways) or bronchospasm (airway spasms, leading to narrowing of the airways)
- Pharyngitis, sinusitis, bronchitis, and asthma in heavy users
- Possible serious effects on 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 found 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 people 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 Food and Drug Administration (dronabinol) for these purposes, use of whole marijuana remains hugely controversial. Currently, cannabis is illegal even for medical use under federal law.