Cannabis for PTSD in 2019: The Systematic Evidence Was Still Thin Despite Growing Interest | Research

The takeaway

A systematic review of all published evidence found promising signals — especially nabilone for nightmares — but not enough rigorous research to confirm cannabis effectively treats PTSD.

Veterans or trauma survivors considering cannabis for PTSD who want to know what the evidence actually supports as of 2019.

What the researchers found

This systematic review gathered everything published through May 2019 on cannabis and synthetic cannabinoids for PTSD. The interest was clearly growing: patients were increasingly turning to cannabis, and several U.S. states listed PTSD as a qualifying condition for medical marijuana.

The most consistent finding across studies was nabilone's effectiveness for PTSD-related nightmares and sleep disturbance. Several studies reported significant reductions in nightmare frequency and severity. For broader PTSD symptoms — hyperarousal, avoidance, re-experiencing — the results were more mixed. Some observational studies showed symptom improvement, but the methodological quality was generally low.

The reviewers found that most available evidence came from case reports, case series, and open-label studies rather than randomized controlled trials. The gap between patient demand and scientific evidence remained wide.

Why it matters

By 2019, cannabis for PTSD had become one of the most politically charged topics in medical marijuana debates. Veterans' groups advocated strongly for access. States were adding PTSD to qualifying conditions. But this review showed the evidence base hadn't kept pace with the policy. The strongest signal — nabilone for nightmares — was specific and replicable, but the broader claim that cannabis treats PTSD remained unsupported by rigorous evidence.

That doesn't mean cannabis doesn't help. It means the research hadn't been done properly enough to say either way with confidence.

The numbers in context

• Nabilone: most consistent evidence, particularly for nightmare reduction

• Most evidence from case reports, case series, and open-label studies

• Searched through May 2019 across three databases

• PTSD is a qualifying condition for medical cannabis in multiple U.S. states

How the study worked

Systematic review following PRISMA guidelines. Searched PubMed, Cochrane Library, and Web of Science through May 2019. Included all study types reporting on cannabis or synthetic cannabinoids for PTSD treatment. Organized results by substance type (plant-based cannabis vs synthetic cannabinoids).

Who was studied

Systematic review of literature up to May 2019 on cannabis and synthetic cannabinoids for PTSD.

What this study cannot tell us

Most included studies were low quality (case reports, case series, open-label designs). Publication bias likely favored positive results. Cannabis products varied widely across studies in type, dose, and route. Cannot distinguish between symptom improvement and general anxiolytic effects. Search was limited to three databases.

How to read the evidence

Systematic review with proper methodology, but the underlying studies were mostly low-quality observational designs. The review is rigorous; the evidence it found was not.

When this study was published

Published in 2019. Some additional RCTs have been published since, though the evidence base remains limited.

The bigger picture

This review, combined with the earlier Steenkamp 2017 review (RTHC-00044), paints a consistent picture: two years of additional research hadn't substantially closed the evidence gap. The endocannabinoid system's role in stress and fear processing remained biologically compelling, nabilone for nightmares remained the standout finding, and the need for large randomized controlled trials remained urgent.

Replication

Not stated in abstract.

Funding

Not reported in abstract.

Conflicts of interest

Not reported in abstract.

Questions still open

Why hasn't the research quality caught up with patient demand for cannabis as PTSD treatment?
Is nabilone specifically effective for nightmares, or would whole-plant cannabis work too?
Could cannabis be effective for specific PTSD symptom clusters (like sleep) but not others?

Common questions

Does cannabis help PTSD?

The most consistent finding is that nabilone (a synthetic cannabinoid) helps with PTSD nightmares. For other PTSD symptoms, the evidence was too limited and low-quality to draw conclusions as of 2019.

Should I use cannabis for my PTSD?

The science couldn't answer that definitively as of this review. Nabilone for nightmares had the best evidence. For broader PTSD treatment, the research wasn't rigorous enough to confirm or deny benefit.

Read the original research

Use of medicinal cannabis and synthetic cannabinoids in post-traumatic stress disorder (PTSD): A systematic review

Medicina (Kaunas), 55(9), 525

Medicina (Kaunas) is a peer-reviewed journal focusing on medical research.

View on PubMed ↗Publisher’s paper ↗

Citation

Orsolini, Laura; Chiappini, Stefania; Volpe, Umberto; De Berardis, Domenico; Latini, Roberto; Papanti, Gabriele Duccio; Corkery, John Martin. (2019). Use of medicinal cannabis and synthetic cannabinoids in post-traumatic stress disorder (PTSD): A systematic review. Medicina (Kaunas), 55(9), 525. https://doi.org/10.3390/medicina55090525