Marijuana has several negative physical & mental effects.
Use of marijuana may impair or reduce short-term memory and comprehension, alter sense of time, and reduce the ability to perform tasks requiring concentration and coordination, such as driving a car.
The physical effects, particularly on developing adolescents, can be far more acute. Studies have shown that marijuana can lower testosterone levels in men. Testosterone controls hair and beard growth, development of the penis, muscle mass, and voice changes at puberty. Marijuana use can also lower sperm counts possibly resulting in difficulty having children. Females who use marijuana can, over time, increase levels of testosterone which can result in increased facial and body hair and acne. Studies also suggest that chronic use of marijuana may adversely affect reproductive functioning in women.
Source: NE Communities Against Subtance Abuse
Marijuana is harmful to the user.
Marijuana is harmful both physically and psychologically. Marijuana causes the same heart and lung problems as cigarette smoking. Actually, worse, because pot-smokers inhale deeply and never use filters. The smoking-related diseases, lung cancer, heart attacks, emphysema, all can be caused by smoking marijuana as well. That is why no medical organization will ever approve or recommend any drug that is smoked.
Marijuana use decreases short-term memory, concentration, coordination, and ability to solve problems. It also causes loss of motivation. These problems hit adolescents the hardest, and teens who smoke marijuana regularly get worse grades, are less likely to finish school and earn less money as adults.
Marijuana use often causes panic attacks and chronic anxiety, and can cause paranoia. These are serious psychiatric problems.
Marijuana use affects a driver's concentration, perception, coordination, and reaction time, causing increased risk of accidents. Montana checks for marijuana in the bloodstream of drivers involved in fatal accidents, and found that fatal accidents caused by pot-smoking drivers increased by 25 percent when their medical marijuana law went into effect. So much for harmless!
Also, marijuana is an addictive drug. About 6-10 percent of regular users get addicted, the same rate seen with alcohol. People addicted to pot have the same problems as people addicted to any other drug; relationship break-ups and divorce, trouble keeping jobs, and increased violence and aggression.
Marijuana is even more harmful to seriously ill people.
The harmful effects of marijuana are even greater for seriously ill people, the very people that claim to need it! Smoking pot damages the immune system, leaving immune-suppressed patients more vulnerable to infection. This could be really bad for AIDS patients. With respect to multiple sclerosis, the National MS Society stated that "coordination, cognition (thinking and memory) and other functions affected by MS could be worsened" by marijuana.
Marijuana use has been shown to be associated with several illnesses.
Marijuana has been associated with lung cancer. A recent study by the Canadian government found cannabis contained more toxic substances than tobacco smoke.
- It contained 20 times more ammonia, (a carcinogen) and
- five times more of hydrogen cyanide (which can cause heart disease) and
- of nitrogen oxides, (which can cause lung damage) than tobacco smoke.
Marijuana use has been linked to psychosis by several peer-reviewed studies. More recently, the Dunedin Multidisciplinary Health and Development Study (New Zealand) published research showing an increased risk of psychosis for marijuana users with a certain genetic predisposition, held by 25% of the population. In 2007, a study published in The Lancet and a poll of mental health experts showed that a growing number of medical health practitioners are convinced that marijuana use increases susceptibility to mental illness, accounting for 14% of United Kingdom psychosis cases.
Loss of Short Term Memory; Lowers Motor Skills can be Hazardous to Human Life.
Although long terms effects of marijuana use is polarised in the scientific community preventing any concrete consensus of the effects of marijuana, short term effects of marijuana are well documented. Effects such as short-term memory and attention loss, loss of motor skills and dexterity, reduced reaction time, and lower abilities to perform skilled activities can be hazardous to human life if combined with potentially hazardous activities such as driving. Cannabis use can also lead to anxiety and panic reactions. There is also evidence that some of the above effect can become permanent with heavy usage.
Multiple studies have shown that chronic heavy marijuana smoking is connected with increased symptoms of chronic bronchitis, such as coughing, production of sputum, and wheezing. Lung function is also significantly poorer and there is a significantly greater amount of abnormalities in the large airways of marijuana smokers than in non-smokers. All of these health issues can be exacerbated by marijuana's addictive qualities, that may possibly lead to a marijuana dependence syndrome.
Source: Marijuana Addiction Information and Treatment