People have used marijuana as a medical treatment for thousands of years. Marijuana has been hailed as a prescription for many ills and physicians once used it to stimulate the appetite, relieve chronic pain, and treat asthma and migraines. Many people are not aware of the fact that this has been so even in modern America, as this plant was listed in the US Pharmacopeia, a list of the approved drugs in the United States, up until the 1940s.
Marijuana: Statistical Data
There were an estimated 2.6 million new marijuana users in 2001. This isn't anything unusual and this figure is similar to the figures revealed in the research that has been performed each year since 1995. In 2002, over 14 million Americans age 12 and older have used marijuana at least once in the month prior to being surveyed, and 12.2 percent of the marijuana users who have been using it the previous year, used marijuana on 300 or more days in the past 12 months. This means that 3.1 million people are using marijuana on a daily or almost daily basis over a 12-month period.
According to the 2015 National Survey on Drug Use and Health, 22.2 million people have used marijuana in the past month, and its use is more prevalent among men than women, however, this gender gap has widened in the last decade.
Percentage of 8th-Graders Who Have Used Marijuana:
Monitoring the Future Study, 2003
What Exactly Is Marijuana?
Marijuana, also called the grass, pot, or weed, is the common name for a crude drug made from the Cannabis sativa plant. It is a green, brown, or gray mixture of dried, shredded leaves, stems, seeds, and flowers of this plant. Other forms of cannabis include:
- Hash oil
Marijuana is usually smoked as a cigarette called a joint, or in a pipe or a bong. Marijuana is also being used as a blunt, which is a cigar that has been emptied of tobacco and refilled with marijuana, sometimes in combination with another drug, such as crack. It can also be mixed into foods or used to brew tea.
Human Consumption Of Marijuana
Smoking is one of the most common marijuana usage methods. There are several methods of smoking cannabis, and the most popular ones include the joint, the bong, the pipe, the shotgun, and the one-hitter. To create a joint, cannabis is rolled up into a cigarette, using a rolling paper. Cannabis cigars or blunts can also be created by using the wrapper of a standard cigar.
A bong is a water pipe through which cannabis smoke is filtered. Marijuana pipes are usually made of blown glass, wood, or non-reactive metals.
A shotgun involves two people. During the procedure, one person takes a hit and then puts the joint into his mouth, while another person then places his mouth over the front end, and the first person exhales through the joint.
Cannabis sativa may be consumed orally by blending it with ethanol or lipids. What are the “benefits” of this way of marijuana consumption? It takes longer for the effects of the weed to start, but they last longer and may be perceived as more physical than mental.
Cannabis can be heated to a temperature of about 185 °C. At this temperature, all the active ingredients of marijuana are released into a gaseous form.
Knifing is a process in which the tips of two knives are heated to a very high temperature, and then the marijuana is pressed between the heated knife-tips, rapidly combusting it. A consumer then uses plastic bottle-top, empty pen, or other hollow tube or funnel to inhale the vapors.
There are several effects of marijuana and some of the most common ones are :
- Impairment of the short-term memory in some users – It is proven that Marijuana's damage to short-term memory seems to occur because THC alters the way in which information is processed by some parts of the brain such as the hippocampus
- Enhancement of many other drug effects such as alcohol, ecstasy, tobacco, heroin, cocaine…
- Auditory or visual hallucinations
- Increased appetite
- Induced sense of novelty
- Increased or decreased sexual pleasure
- Increased sensations
- Increased awareness of patterns and colors
- Respect for music and other arts
- Increased mental activity
- Meditative states of mind
- Gain or loss of some inhibitions
- Varying degrees of euphoria, ranging from feelings of general well-being to lengthy pointless laughter
- Relaxation or stress reduction
- Mild tachycardia
- Mild, temporary dry mouth
- Varying amounts of paranoia and anxiety in some users
It is proven that people who smoke marijuana regularly may have many of the same respiratory problems that tobacco smokers have.  These problems include a daily cough and phlegm production, more frequent acute chest illnesses, a heightened risk of lung infections and a greater tendency toward obstructed airways. In fact, more cancer-causing agents (and anti-cancer agents) have been found in marijuana smoke than in tobacco smoke.
Active Components Of Marijuana
The active ingredient in marijuana is a substance called delta-9-tetrahydrocannabinol (THC) — a very strong psychoactive substance. THC is responsible for the potency and effects of marijuana intoxication. Different types of marijuana have different levels of THC, but it is evidenced that, over the past two decades, THC levels of marijuana in the United States have increased.
Marijuana is a complex plant with different compounds and different effects on people. 
Other active components include:
- Cannabinol and cannabidiol
- These compounds have some of the properties of THC but cause less psychoactive effects.
- Dronabinol (Marinol): a man-made version of THC available by prescription. It's used to prevent nausea and vomiting after cancer chemotherapy and to increase appetite in people with AIDS.
Weed: Mechanism Of Action
When smoked or ingested, THC and other active components that can be found in marijuana target and attach themselves to two types of receptors on the cells in the body.
- CB1 receptors: These receptors are found mainly in the brain, especially in the areas that control body movement, memory and even vomiting. This is why marijuana affects balance and coordination and impairs short-term memory and learning, and why it can be useful in treating nausea, pain and loss of appetite.
- CB2 receptors: These receptors are found mainly in the immune system tissue, such as your spleen and lymph nodes, although in much smaller numbers.
How Fast Do The Effects Of Marijuana Occur And How Long Do They Last?
- When marijuana is smoked, its ingredients reach their peak levels in the body within minutes and the effects can last up to an hour and a half.
- When marijuana is eaten, the ingredients may take several hours to reach their peak levels in your body, and their effects may last for hours.
- When used as a pill or an oral capsule (Marinol), marijuana takes effect in about 30 minutes and can continue to stimulate the appetite for more than a day.
Possible Medical Uses Of Marijuana
Experts who have been studying marijuana's potential and the medical uses of marijuana found out that it can be used to treat many different conditions in order to cure them or speed up the recovery time. Some of these conditions are:
Glaucoma And High Blood Pressure
This disease is caused by increased pressure in the eyeball, which can lead to vision loss and complete blindness. However, the experts in this field discovered that smoking marijuana reduces the pressure in the eyes.  The exact reason is still unknown. Smoking marijuana may reduce the blood pressure too, which also isn't explained yet.
A problem with this type of therapy is that it can lose its effectiveness over time. Experts are working on the development of cannabis-based medications that can be put directly on the eyes.
People have used marijuana for pain relief for hundreds of years. It is proven that THC may work as a mild pain reliever in treating cancer pain. 
Several pieces of research done in the past have shown the effectiveness of cannabis in the treatment of the muscle spasms and pain in multiple sclerosis. Multiple sclerosis is a serious disease of the nervous system which can cause a lot of pain because of the severe nerve damage. It is proven that marijuana can protect nerves from the kind of damage that occurs due to this disease. 
There are several other effects that can be considered beneficial such as:
- Increased appetite due to the fact that food subjectively tastes better.
- Reduced nausea.
- Dilation of air sacs in lungs, resulting in deeper respiration.
- Increase in productive coughs.
- Dilation of blood vessels (vasodilation).
- Increased blood flow and heart rate.
- Reddening of the conjunctivae.
- Induces drowsiness, so it can be beneficial to sufferers of insomnia and sleep deprivation.
- Reduced stress.
Is There A Lethal Dose Of Weed?
It is generally considered impossible to achieve a lethal overdose by smoking cannabis. According to the several pieces of research and experiments, the lethal dose for 50% of rats tested is 42 mg/kg of body weight although it was done by inhalation. If we transfer these results to humans, that is equivalent to a 75 kg man ingesting 21-gram cigarettes of high-potency cannabis buds at once. 
Marijuana Addiction And Tolerance
When a person is chemically dependent on marijuana, it additionally means increased tolerance — the person needs to use more and more marijuana to get the same effect. The most common marijuana withdrawal symptoms are:
- Trouble sleeping
A lot of young marijuana users are saying that it’s not possible to be addicted to marijuana. This, of course, isn’t true. As with any other drug or alcohol, long-term marijuana use can lead to addiction for some people, which means that they use the drug compulsively even though it interferes with their family life, school, work, and recreational activities.
About 1 in 6 people who start using weed as teens and 25 to 50 percent of those who use it every day become addicted.  Marijuana is also a gateway drug to use of other illegal drugs: long-term studies of drug use patterns show that most high school students who use other illegal drugs have tried marijuana first , although it wouldn’t be fair to say that cannabis is responsible for drug addiction — many young people who use marijuana do not go on to use other drugs.