The following originally appeared on The Upshot (copyright 2015, The New York Times Company).
It is becoming easier to get marijuana, legally. In the last 20 years or so, 23 states, as well as the District of Columbia, have passed laws that make it legal to use marijuana for medical treatments. So have some countries, like Austria, Canada, Finland, Germany, Israel and Spain.
Advocates believe that this has allowed many with intractable medical problems to receive a safe and effective therapy. Opponents argue that these benefits are overblown, and that advocates ignore the harms of marijuana. Mostly, opponents say that the real objective of medical marijuana is to make it easier for people to obtain it for recreational purposes.
Both sides have a point. Research exists, however, that can help clarify what we do and don’t know about medical marijuana.
A recent systematic review published in The Journal of the American Medical Association looked at all randomized controlled trials of cannabis or cannabinoids to treat medical conditions. They found 79 trials involving more than 6,400 participants. A lot of the trials did show some improvements in symptoms, but most of those did not achieve statistical significance. Some did, however.
Medical marijuana was associated with some pretty impressive improvements in complete resolution of nausea and vomiting due to chemotherapy (47 percent of those using it versus 20 percent of controls). It also increased the number of people who had resolution of pain (37 percent up from 31 percent). It was shown to reduce pain ratings by about half a point on a 10-point scale, and to reduce spasticity in multiple sclerosis or paraplegia in a similar manner.
Those aren’t insignificant results and they are supported by other studies that have confirmed that marijuana and cannabinoids can help with refractory pain. But most researchers stress that they should be considered only when other therapies have failed.
There’s a little bit of evidence that marijuana might help with anxiety disorders and with sleep. The trials are at high risk of bias, though, and there are very few of them. The combined trials did not show that it helps with psychosis, glaucoma or depression. Reviews show that trials also failed to support its use for dementia, epilepsy, Tourette’s syndrome or schizophrenia.
There are also side effects of marijuana to consider. They include dizziness, dry mouth, nausea, fatigue, drowsiness, vomiting, disorientation, confusion, loss of balance and hallucination. There’s also the potential for abuse. Those need to be weighed against any benefits. Let’s be frank: There’s just no way that the Food and Drug Administration would approve any other drug with these side effects and the relatively scant evidence, mostly from small studies, of any health benefits.
Or course, arguing that no evidence currently exists is not the same as arguing that no evidence could be found. For too long, the federal government has made studying the use of marijuana nearly impossible. The Drug Enforcement Administration has classified marijuana as a Schedule 1 drug, meaning that it has no medical value and a high potential for abuse. Even if researchers jumped through the many hoops to get research approved, it was almost impossible for them to obtain the drug.
The only place scientists can get marijuana for research in the United States is the University of Mississippi, which has an exclusive contract with the federal government to grow the plant for study. Regardless of how many studies could be done, the university has until recently been allowed to grow only 21 kilograms annually, enough for about 50,000 joints.
Last year the government raised that quota to 650 kilograms. Research became even easier last month when the federal government removed an extra hurdle of approval researchers needed in order to study marijuana’s medicinal purposes.
This means that large trials, like those done by pharmaceutical companies, might be possible in the future. These will take years to complete, though. It’s still likely that for the majority of things that marijuana is prescribed for now, evidence will be unavailable for some time.
Many of the drugs that are approved for chronic pain, such as opioids, don’t have a lot of evidence supporting long-term use. These drugs are also extremely dangerous. Just recently, researchers published a paper that argued that deaths from painkillers are lower in states that have approved medical marijuana.
Because of that, marijuana’s benefits seem to outweigh the potential harms for people who have intractable nausea and vomiting caused by chemotherapy, or severe and intractable pain from chronic illnesses that won’t respond to other therapies. But people who fall into those categories are not typically the people asking for medical marijuana.
The vast majority of patients who seek a doctor’s authorization for pot do not have cancer, glaucoma or other serious illnesses. In Oregon, “severe pain” is reported as a condition requiring treatment in 93 percent of patients, while fewer than 6 percent had cancer. Most people are getting prescriptions for conditions where cannabis is not clearly effective, and for symptoms that are very subjective and potentially faked.
When Prohibition became the law of the land, one of the only ways to get alcohol was to get a prescription from a physician. In 1921, a coalition of brewers, doctors and the public tried to lobby Congress that beer was a “vital medicine.” The American Medical Association disagreed, using the same arguments they use today to argue that marijuana shouldn’t be handed out as therapy. They said it was not proved to work, that it was not a targeted therapy, that most people who asked for it didn’t meet strict criteria and that doctors should not be in the business of doling it out.
Promising research continues that might support possible use of marijuana in certain areas. For other afflictions, further research would be needed to justify any prescriptions. Should marijuana become legal, however, it’s likely that many of these debates will just go away, as they did for alcohol.