To say that marijuana’s making a comeback would be an understatement. Since California enacted a medical marijuana law in 1996, 20 other states and the District of Columbia have followed suit, with eight of them passing laws in the past four years alone. Two of them — Washington and Colorado — have even passed full-blown legalization of the drug. And none of that includes the many states that are currently in the process, such as New York and Minnesota. This huge shift in public opinion can be credited, in large part, to a wide range of studies and patient testimonies supporting the drug’s health benefits. So, what are some of them?

Stress, Anxiety, and PTSD — It’s a Mixed Bag

No matter how you ingest marijuana, there are possible side effects to the drug — pro-pot advocates will claim they’re never as bad as pharmaceutical side effects — including anxiety and paranoia. These effects can subsequently lead to a higher blood pressure, arrhythmia, and other effects common to anxiety. In this way, it’s a gamble when taking marijuana. For those who know how much they’re taking and what to expect, however, may experience the opposite effect: calm, relaxation, and happiness.

For people with post-traumatic stress disorder (PTSD), one of the worst possible anxiety disorders, marijuana might be able to alleviate symptoms. Although there’s a scarcity of human research into the association, anecdotal evidence is heavy, and states, such as Main and New Hampshire, have begun allowing its use. The Department of Health and Human Services also signed off recently, on a study to test its benefits in PTSD patients.

The use of marijuana for anxiety disorders, and just plain stress, comes from the fact that the brain naturally produces cannabinoids, which are the active chemicals in marijuana — namely, delta-9 tetrahydrocannabinol, or THC — and what help regulate how fear is processed in the brain.

A May 2013 study found that people with PTSD showed lower levels of a certain endocannabinoid known as anandamide in the area of their brains associated with fear and anxiety. Thus, fewer cannabinoid receptors were being activated, spurring PTSD along. In theory, using marijuana would boost concentrations of these beneficial cannabinoids, reducing symptoms of PTSD. “We know very well that people with PTSD who use marijuana often experience more relief from their symptoms than they do from antidepressants and other psychiatric medications,” said lead author Dr. Alexander Neumeister, of the Departments of Psychiatry and Radiology at New York University, in a press release.

In part, these calming effects could be the reasons why marijuana use has been linked to a 10 percent reduction in suicide rates, while also being considered for use in some Swiss prisons.

Cerebral Palsy and Other Neurodegenerative Diseases

Neurodegenerative diseases affect millions of people in the U.S. Parkinson’s disease, for example, affects an estimated one million people, while cerebral palsy affects as many as 764,000 children and adults. These diseases and more are all debilitating in their own way, as they affect the nervous system’s ability to connect with the brain, therefore affecting a person’s ability to move. Marijuana has shown huge promise in saving these people.

Multiple sclerosis (MS), which occurs when the immune system attacks the nerve’s myelin sheaths, causes the nerves to become unable to communicate with each other. In turn, this causes weakness in limbs, partial to complete loss of vision, and tremors. Studies on marijuana use among animals with MS showed that THC and other cannabinoids were able to target the inflammation-causing cells produced by the immune system, subsequently leading to less destruction of myelin. Another UK study found that 12 weeks of marijuana treatment helped relieve muscle stiffness in 30 percent of almost 300 patients suffering from MS.

Marijuana has also been shown to reduce symptoms of Parkinson’s disease (PD), which include rigid muscles, slow movement, and tremors. In a study of 22 patients who were all about 66 years old, tremor scores dropped after using marijuana. “The study suggests that cannabis might have a place in the therapeutic armamentarium of PD,” the researchers wrote. “Larger, controlled studies are need to verify the results.”

In such patients, the results really do need to be seen to be believed. In December, Medical Daily reported the story of Jacqueline Patterson, a Missouri mother of four whose cerebral palsy had left her with a severe stutter caused by muscle stiffness, which has also caused her severe pain and the inability to use her right arm correctly. With marijuana, she becomes a totally different person, able to speak, move, and overall become less tense.

Cancer

The big one right here. Pretty much any state that legalizes marijuana for medical use lists cancer as one of the first conditions it can be used for. People undergoing chemotherapy for whatever their cancer may be often experience nausea, vomiting, loss of appetite, and pain, according to the National Institutes of Health (NIH). Marijuana has been shown to alleviate all of these side effects. In fact, two FDA-approved medications, dronabinol and nabilone, are derived from THC and used in cancer patients and HIV/AIDS patients to treat nausea and vomiting. Dronabinol was also shown last year to ease pain in cancer patients. As for increasing appetite, well, they don’t call it the munchies for nothing.

Beyond chemo, there’s also evidence that marijuana can help prevent the growth of tumors. According to the NIH, another cannabinoid, cannabidiol, has been shown to relieve pain as well as lower inflammation. Cannabinoids such as these have been shown to block cell growth, prevent the growth of blood vessels that aid metastasis (the spread of tumors), and kill tumor cells. Some researchers have even found a way to harness this power without the psychoactive effects.

“Cannabinoids have a complex action; it hits a number of important processes that cancers need to survive,” oncologist Dr. Wai Liu told The Huffington Post. “For that reason, it has really good potential over other drugs that only have one function. I am impressed by its activity profile, and feel it has a great future, especially if used with standard chemotherapies.”

For Recreational Users

As marijuana becomes further engrained in American culture, some might ask, is it better to smoke weed or consume it through mediums like edibles and oils. It is indeed better to eat it, as it doesn’t involve inhaling the harmful tars produced through the combustion of rolling paper. But even eating it may have its caveats, as getting the proper dose can be difficult. By far, the best way to toke healthily is to use a vaporizer, which heat the cannabis just enough to release active cannabinoids without releasing smoke and toxins. “Vaporizer users are only 40 percent as likely to report respiratory symptoms as users who do not vaporize,” researchers of a 2007 study wrote. “Regular users of joints, blunts, pipes, and water pipes might decrease respiratory symptoms by switching to a vaporizer.”