Prescription drugs kill about 100,000 people in the world each year. Off the top of your head, do you know how many deaths are caused by using marijuana, either medicinally or recreationally?

"There are no deaths from cannabis use. Anywhere. You can't find one," said Dr. Lester Grinspoon, professor emeritus at Harvard Medical School.

Believe it: In 10,000 years of known use of cannabis, there's never been a single death attributed to marijuana.

"I've heard you have to smoke something like 15,000 joints in 20 minutes to get a toxic amount of delta-9 tetrahydrocannibinol," said Dr. Paul Hornby, a biochemist and human pathologist who also happens to be one of the leading authorities on cannabis research. "I challenge anybody to do that."

Meanwhile, it's a fact that anyone can die from ingesting too much aspirin, or too much coffee, or too much wine. Marijuana, on the other hand, medical or not, is not only non-lethal, but likely beneficial. Several studies, some published as recently as a few months ago, have shown that marijuana can even be good for your health, and could help treat conditions better than the solutions being cooked up in the labs.

The late Dr. Tod Mikuriya, a former national administrator of the U.S. government's marijuana research programs, appeared in a film about the business of marijuana prohibition shortly before his 2007 death called "The Union." (The full movie is available on both Netflix and YouTube.)

"After dealing with about 10,000 patents in the last 15 years, I'd say about 200 different medical conditions respond favorably to cannabis," Mikuriya said.

We won't go through all 200 conditions here, but here are 10 of the most notable, common conditions, afflictions and diseases that marijuana has been proven to help.

Alzheimer's disease - In 2006, the Scripps Research Institute in California discovered that delta-9-tetrahydrocannabinol (THC), the active ingredient in marijuana, can prevent an enzyme called acetylcholinesterase from accelerating the formation of "Alzheimer's plaques" in the brain, as well as protein clumps that can inhibit cognition and memory, more effectively than commercially marketed drugs.

Epilepsy - A study performed by researchers at Virginia Commonwealth University discovered that ingredients found in natural marijuana "play a critical role in controlling spontaneous seizures in epilepsy." Dr. Robert J. DeLorenzo, professor of neurology at the VCU School of Medicine, added that "Although marijuana is illegal in the United States, individuals both here and abroad report that marijuana has been therapeutic for them in the treatment of a variety of ailments, including epilepsy."

Multiple sclerosis - It's long been believed that smoking pot helps MS patients, and a study published as recently as May provided yet another clinical trial as evidence of marijuana's impact on multiple sclerosis patients with muscle spasticity. Even though the drug has been known to cause dizziness and fatigue in some users, most MS patients report marijuana not only helps ease the pain in their arms and legs when they painfully contract, but also helps them just "feel good." How many prescription drugs can say their side effects include "happiness"?

Glaucoma - Since the 1970s, studies have called medical marijuana an effective treatment against glaucoma, one of the leading causes of blindness in the world. Researchers say marijuana helps reduce and relieve the intraocular pressure that causes optic nerve damage, but the proponents say it helps "reverse deterioration," too.

Arthritis - Marijuana proves useful for many types of chronic pain conditions, but patients with rheumatoid arthritis report less pain, reduced inflammation and more sleep. However, this is not to say that arthritis patients should exchange their medication with pot; marijuana eases the pain, but it does nothing to ameliorate or curb the disease.

Depression - A study on addictive behaviors published by USC and SUNY Albany in 2005, whose 4,400 participants made it the largest investigation of marijuana and depression to date, found that "those who consume marijuana occasionally or even daily have lower levels of depressive symptoms than those who have never tried marijuana." The study added that "weekly users had less depressed mood, more positive affect, and fewer somatic complaints than non-users."

Anxiety - An article published in the April 2010 edition of the Harvard Mental Health Letter, "Medical marijuana and the mind," said that while "many recreational users say that smoking marijuana calms them down, for others it has the opposite effect. ... Studies report that about 20 to 30 percent of recreational users experience such problems after smoking marijuana." The article did not mention which "studies" supported this fact, and most marijuana users would call this claim totally erroneous. Here's a story from Patsy Eagan of Elle Magazine, who describes how she prefers marijuana to treat her anxiety over prescription drugs.

Hepatitis C - A 2006 study performed by researchers at the University of California at San Francisco found that marijuana helps improve the effectiveness of drug therapy for hepatitis C, an infection that roughly 3 million Americans contract each year. Hepatitis C medications often have severe side effects like loss of appetite, depression, nausea, muscle aches and extreme fatigue. Patients that smoked marijuana every day or two found that not only did they complete the therapy, but that the marijuana even made it more effective in achieving a "sustained virological response," which is the gold standard in therapy, meaning there was no sign of the virus left in their bodies.

Morning sickness - In a peer-reviewed study, researchers at the British Columbia Compassion Club Society found that 92 percent of women found marijuana's effect on morning sickness symptoms as either "very effective" or effective." Read the first-hand account from Dr. Wei-Ni Lin Curry, who describes how medical marijuana saved her from a potentially life-threatening situation:

"Within two weeks of my daughter's conception, I became desperately nauseated and vomited throughout the day and night. ... I vomited bile of every shade, and soon began retching up blood. ... I felt so helpless and distraught that I went to the abortion clinic twice, but both times I left without going through the with procedure. ... Finally I decide to try medical cannabis. ... Just one to two little puffs at night, and if I needed in the morning, resulted in an entire day of wellness. I went from not eating, not drinking, not functioning, and continually vomiting and bleeding from two orifices to being completely cured. ... Not only did the cannabis save my [life] during the duration of my hyperemesis, it saved the life of the child within my womb."

Most prospective mothers will worry about the effect of ingesting marijuana in any form on their baby's development. The only study that showed any effect from smoking pot came from the University of Pittsburgh's School of Medicine in 2008, which showed that heavy smoking "during the first trimester was associated with lower verbal reasoning," while "heavy use during the second trimester predicted deficits in the composite, short-term memory, and quantitative scores." Though this singular study may be enough to scare away some mothers, the majority of studies say prenatal pot exposure "is not a major prognostic factor regarding the outcome of pregnancy," and that "marijuana has no reliable impact on birth size, length of gestation ... or the occurrence of physical abnormalities." Compared to mothers that used tobacco and alcohol, all of whom showed "increased risk of suspect or definite psychotic symptoms (in offspring)," mothers' cannabis use "was not associated with psychotic symptoms" in their children.

Cancer, HIV/AIDS and chemotherapy - Though the drug is illegal in the U.S., the FDA and American Cancer Society agree that the active ingredients in marijuana, or cannabinoids, have been approved by officials to "relieve nausea and vomiting and increase appetite in people with cancer and AIDS." The American Cancer Society says that "marijuana has anti-bacterial properties, inhibits tumor growth, and enlarges the airways, which they believe can ease the severity of asthma attacks."

Marijuana: Why Is It Illegal Again?

This is too big of a question to answer in just one single article, but looking at cannabis through the lens of its medical properties, there seem to be few, if any, reasons to keep marijuana off the market. It doesn't kill, and while it may not be as effective as other treatments, it doesn't seem to get in the way much.

When Mikuriya was asked if there was a product out there today - anything - that has as many benefits as medical marijuana, he said simply: "No."

Medical marijuana may be beneficial for everyone's health, but it's not very healthy for the pockets of the pharmaceutical companies. And unfortunately for Americans in need of a cheap, all-natural alternative medicine, the pharmaceutical industry is the biggest industry in America with powerful connections in high places. And they don't like marijuana. At all.

"It's unlimited," Hornby said of marijuana. "Grow more, get more medicine. Pharmaceutical companies don't want you growing your own medicine."

The idea of legalizing a cheap, all-natural medicine that grows out of the dirt is a threat to the pharmaceutical industry's bottom line.

Dr. James Hudson, professor emeritus at University of British Columbia's Department of Pathology and Lab Medicine, said pharmaceutical companies have a great incentive to recreate the organic compounds in marijuana and sell a drug from it, rather than just release the all-natural version to the public.

"The prime motivation behind any drug company is to make money, and as much money as possible. In the case of a synthetic compound, if it's only an ingredient from the cannabis, they can formulate that as a drug and make a lot more money off of it."

Since no company can patent a plant, pharmaceutical industries are incentivized to keep cannabis and industrial hemp illegal as they try to recreate the same drug with the same effects. Obviously, there is a great deal of "double talk" in this argument - How can the government prohibit marijuana but allow an identical drug with identical effects? - but ultimately, it comes down to money.

"There's no money to be made off natural plants," said Dana Larsen, founding editor of Cannabis Culture magazine. "If you use a natural medicine that you can grow in your own home that costs pennies to use, you're going to do that."

Yet, the facts remain: Prescription drugs, while legal, are experimental, dangerous and often toxic. Prescription drugs continue to kill tens of thousands, if not hundreds of thousands, of Americans each year; meanwhile, marijuana has never been the direct contributor to a single death. Maybe we should focus less on making natural plants extinct and focus more on controlling the drugs that we're actually responsible for.