Millions of people use marijuana — a combination of shredded leaves, stems and flower buds of the Cannabis plant; some recreationally and some for its supposed medical benefits. While the popular weed has been used for medicinal purposes for centuries, the debate on its effectiveness continues.
Some of the earliest discoveries of marijuana's properties date back to 2700 B.C. in China, where it was described in pharmacopoeias. The ancient Greeks and Egyptians used it for ailments, and word of the herb spread across Europe. In 1484, Pope Innocent VIII banned hashish, a concentrated resin produced from the flowers of the Cannabis plant. In the 20th century, the Rastafari religious movement incorporated smoking marijuana into the faith as a means of spiritual discovery.
Compounds in marijuana can relieve pain, combat nausea and stimulate appetite. But whether these health benefits outweigh the risks of legalized marijuana has fueled a debate and legislative conundrum across the United States. In more than 15 states, local police may consider an individual's marijuana use legal, while federal law prohibits it.
Unlike many abused drugs, an overdose of marijuana is not lethal, according to the National Cancer Institute. Although marijuana can be addictive for some, the potential for forming an addiction to marijuana is lower than some prescription drugs and other abused drugs.
However, marijuana has side effects. The primary psychoactive chemical in marijuana is THC, or tetrahydrocannabinol, one of more than 60 cannabinoids (chemicals unique to marijuana). THC binds to cannabinoid receptors, which are concentrated in areas of the brain associated with thinking, memory, pleasure, coordination and time perception.
The effects of marijuana can interfere with attention, judgment and balance. Marijuana also suppresses the immune system, which can be damaging to many people, but useful for others with certain health conditions. Although marijuana has been known to decrease pressure within the eyes, a symptom of the condition glaucoma, research has shown that other drugs may be more effective.
Studies have produced conflicting results on whether smoking marijuana carries a significant cancer risk.According to the American Cancer Society, worldwide research into the benefits and side effects of compounds in marijuana is ongoing. Some compounds in marijuana have already been developed into pharmaceuticals.
Canada, New Zealand and several countries in Europe have approved the nasal spray Sativex, which uses purified cannabinoids derived from marijuana for the treatment of cancer pain and muscle spasms in multiple sclerosis. The U.S. Food and Drug Administration approved two drugs made from synthetic cannabinoids, dronabinol and nabilone, which treat nausea and appetite problems in cancer and HIV patients. Yet the FDA has not approved marijuana in its plant form as a treatment.
During a 2004 congressional testimony, a doctor speaking on behalf of the FDA said marijuana as a “botanical product” is difficult to test for efficacy and safety because the proportions of active chemicals can range greatly from plant to plant. This, he said, can also cause problems for patients trying to use marijuana. But he added that the FDA “will be receptive to sound, scientifically based research into the medicinal uses of botanical marijuana and other cannabinoids.”
Still, more than a dozen states have voted to legalize Cannabis for medical purposes. California was the first state in the country to pass medical marijuana laws in 1996. Dozens of states have followed suit despite existing federal laws that classify marijuana as a Schedule I controlled substance. Most residents of states with medical marijuana laws need to follow a set of guidelines before using the drug; obtain a medical doctor's prescription, obey rules for the maximum weight a person can posses and sign up for a registry of medical marijuana users.