The main active ingredient of marijuana is delta-9-tetrahydrocannabinol (THC), one of more than 60 related leaves of the cannabis (hemp) plant. The leaves and flowers can be ground up in drinks or food, but more often they are dried and smoked in cigarette or pipe. The pure resin, known as hashish, can also be smoked, eaten, or drunk. New breeding and cultivation techniques have raised the THC content of marijuana smoked in the United States as much as ten times over the last 20 years, from an average of 0.4 percent. Some varieties now contain as much as 10 percent.

The effects last two to four hours when marijuana is smoked and five to twelve hours when it is taken by mouth. Although the intoxification varies with psychological setting and social setting, the most common response is a calm, mildly euphoric state in which time slows and sensitivity to sights, sounds, and touch is enhanced. the smoker may feel exhilaration or hilarity and notice a rapid flow of ideas appear before closed eyes: visual perception and body image may undergo subtle changes. It is dangerous to operate complex machinery, including automobiles, under the influence of marijuana, because it slows reaction time and impairs attention and coordination. This impairment persists for at least several hours after the feeling of intoxification has passed.

The main physiologically effects of cannabis are increased appetite, a faster heartbeat, and slightly bloodshot eyes. Although the increased heart rate could be a problem for people with cardiovascular disease, dangerous short-term physical reactions to marijuana are almost unknown. Like many other drugs, it produces a toxic delirium when taken at very high doses, especially by mouth. The symptoms are confusion, agitation, disorientation, loss of coordination, and often hallucinations: the delirium ends when the drug passes out of the body. No human being is known to have died from an overdose. By extrapolation from animal experiments, the ratio of lethal to effective (intoxicating) dose is estimated to be on the order of thousands to one.

The most common disturbing reaction to marijuana is acute anxiety, sometimes accompanied by paranoid thoughts. The user can become fearful and may read hostility or ridicule into the gestures and words of companions. Mounting anxiety may lead to panic. The best way to handle the anxiety and paranoia is calming support and reassurance. The reaction is not a psychosis: there are no hallucinations, and reassurance would not be effective without an ability to test the reality of thoughts and perceptions. Some authorities also refer to a cannabis delusional disorder with feelings of persecution and jealousy. Whether or not this is distinguishable from the anxiety reaction, the treatment is the same--reassurance and waiting for the drug to fade.

At doses commonly used, marijuana impairs memory, perception, judgement, and fine motor skills; increasing the risk of serious accident while performing complex tasks such as driving, operating machinery, or caring for children.

Marijuana impairs driving skills for at least 4-6 hours after smoking a single cigarette. When used in combination with alcohol, driving skills are even more erratic.

Although no instance of human lung cancer has been attributable solely to marijuana smoking, abnormalities suggestive of pre-cancerous lesions have been reported. Since most marijuana smokers also smoke cigarettes, the combined carcinogenic effect must also be investigated. There are more know carcinogens in marijuana smoke than in cigarette smoke. Marijuana has a significant negative effect on gas exchange in the lungs, greater than tobacco.

Smoking marijuana immediately accelerates the heartbeat and, in some persons, increases blood pressure. These changes pose a threat for people with abnormal heart and circulatory conditions, such as high blood pressure and hardening of the arteries.

Marijuana may have serious effects on reproduction. Some studies have shown that women who smoke marijuana during pregnancy give birth to babies with defects similar to the fetal alcohol syndrome.

There is increasing concern about the long-term developmental effects of marijuana use by children and adolescents. Clinicians use the term "amotivational syndrome" to describe the changes seen in some marijuana users. These include apathy, loss of ambition, loss of effectiveness, diminished ability to carry out long-term plans, difficulty in concentrating, and a decline in school or work performance.

New studies show that, in animals, marijuana interferes with the body's immune systems response to various infections and diseases. The significance of this for humans is currently being investigated.

This information has been generously provided by the Alcove, West Jersey Health Systems's Addiction Treatment Program. For further information or for assistance, treatment and referral call Alcove (609) 342-4505.