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Home » Marijuana treatment of PTSD and chronic pain – probably does not work

Marijuana treatment of PTSD and chronic pain – probably does not work

I’ve written extensively about marijuana treatment for various diseases. For example, using it to prevent or treat cancer? No clinical evidence support its use. In fact, a large review of published science on medical marijuana showed little evidence of it having a clinical benefit except for just a few conditions, one of which was chronic pain.

Apparently, there is little scientific evidence to draw conclusions about the benefits and harms of marijuana treatment for patients with posttraumatic stress disorder (PTSD) and chronic pain, according to two studies published recently in the respected journal Annals of Internal Medicine.

Let’s take a look at these two articles and determine what they say about marijuana treatment of PTSD and chronic pain.

Marijuana treatment of PTSD

Posttraumatic stress disorder is a mental disorder that can develop after a person is exposed to a traumatic event, such as sexual assault, warfare, traffic collisions, violent crimes or other threats on a person’s life. Symptoms, which may include disturbing thoughts, feelings, or dreams related to the events, are debilitating to sufferer, causing alterations in how they respond to daily events in life.

The Committee on the Health Effects of Marijuana: An Evidence Review and Research Agenda, published by the influential and prestigious National Academies of Science, Engineering and Medicine, concluded that there was limited evidence that marijuana treatment could improve symptoms of posttraumatic stress disorder. There was one small clinical trial, using nabilone, that showed a positive benefit. However, the study was really small, only 10 patients, meaning it would have to be repeated in a study with thousands of participants before we could accept the findings.

In a systematic review, the top of the hierarchy of evidence in medicinepublished in the Annals of Internal Medicine, O’Neil et al. examined two other systematic reviews, three observational studies, and zero randomized trials. The observational studies looked at marijuana treat vs. nonuse – it found that cannabis did not reduce PTSD symptoms.

The authors concluded that, “evidence is insufficient to draw conclusions about the benefits and harms of plant-based cannabis preparations in patients with PTSD, but several ongoing studies may soon provide important results.”

The whole point of evidence based medicine is to examine the quality of evidence that support (or not supporting) a particular clinical strategy. At this point in time, there is simply insufficient evidence that supports the use of marijuana for treatment of PTSD. Sure, there are some anecdotes that it does help, but that’s not evidence – only a blinded clinical trial can remove confirmation bias so we can tell if there is a clinical benefit.

This happens a lot in the medical marijuana world. Huge claims are made unsupported by real evidence and data.

Marijuana treatment of chronic pain

Chronic pain is physical suffering or discomfort caused by some illness or injury. There isn’t a consensus on the definition of “chronic” pain – some say it’s any pain that lasts more than 30 days, while others say 12 months. Severe chronic pain can lead to a higher mortality rate, and individuals have higher incidence of depression, anxiety and sleep disturbances.

In the report of the National Academies of Science, Engineering and Medicine referenced in the previous section, researchers reviewed the evidence regarding marijuana treatment of chronic pain, and it found strong scientific evidence supporting its use.

However, a new systematic review by Nugent et al. comes to a subtly different conclusion. They did a meta-analysis of 27 chronic pain trials with cannabis. They found that there is limited evidence that suggests that marijuana treatment may alleviate neuropathic pain in some patients. However, there is insufficient evidence supporting its use in other types of chronic pain, such as multiple sclerosis pain and cancer pain.

The Nugent et al. study seemed to have a differing conclusion from the National Academies of Science study. Fortunately, the authors addressed this difference:

Although the overall conclusions seem to differ from our findings, the authors stipulated that the clinical improvements were modest and limited to neuropathic pain, and they underscored the urgent need for better research clarifying the effects of cannabis. Our review augments this report by using a systematic approach on a more focused topic (chronic pain and harms) as well as standard terminology for describing the strength of the body of evidence.

This research seems to extend what the National Academy of Sciences reported, making it more valuable in understanding marijuana treatment of chronic pain.

Furthermore, the researchers found that among general populations, there is actually limited evidence that suggest that cannabis may be associated with an increased risk for adverse mental health effects. These effects include exacerbation of manic symptoms in those with diagnosed bipolar disorder and  suicide death.

Nugent et al. conclude that their study was limited by a lack of methodologically rigorous clinical trials, variability in the quality of cannabis, and other important factors. Like the systematic review of marijuana treatment of PTSD, the current evidence is too weak to support its use in chronic pain.


Yes, future research may change the scientific consensus on marijuana treatment of chronic pain and PTSD. However, only powerful, robust evidence from well-designed, unbiased clinical trials can change the consensus.

And because there seems to be some evidence of risks of adverse effects, especially for mental health, the benefit to cost equation currently may not support its use in these areas.

Dr. Sachin Patel, MD states in the accompanying editorial about these two articles in the Annals of Internal Medicine:

The systematic reviews highlight an alarming lack of high-quality data from which to draw firm conclusions about the efficacy of cannabis for these conditions, for which cannabis is both sanctioned and commonly used.

Yes, there will be comments that “marijuana treatment works for me.” That is an anecdote, and the reason we reject anecdotes as data is because we don’t know if there’s actually an effect, if there’s a placebo effect, or if there’s no correlation whatsoever between cannabis and the condition.

And someone might state that “but evidence may show up in the future.” Well, that’s the argument from ignorance, which states that marijuana treatments work because we haven’t “proven” that they don’t work. Well, that’s not what this article says. It says, there is simply no evidence, at this time, that support its use in chronic pain or PTSD.

If there is better data that either leads to a change in the conclusion that there is little to no evidence that cannabis can treat either PTSD or chronic pain, we will write about it here.



Michael Simpson
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