THC Reduces Trauma-Related Nightmares in Study Involving People With PTSD

For some people with post-traumatic stress disorder (PTSD), the trauma does not end when they wake up; it returns during sleep. Now, a clinical study suggests that a pharmaceutical form of THC may reduce the frequency and intensity of these nightmares.

Nightmares are one of the most prominent symptoms of post-traumatic stress disorder, a condition that can emerge after a person experiences or witnesses a traumatic event. These dreams can cause individuals to relive parts of the trauma while asleep, triggering fear, anxiety, and frequent disruptions to their rest.

Although treatments for post-traumatic stress disorder exist, medications specifically targeting nightmares remain limited. Consequently, researchers investigated whether tetrahydrocannabinol, better known as THC, could help alleviate these symptoms.

The study was conducted across several research centers and involved 171 adults with post-traumatic stress disorder and recurring nightmares. Participants were randomly assigned to two groups: 87 received dronabinol, a medication containing THC, while 84 received a placebo, a substance lacking the active ingredient being studied. The medication or placebo was taken once daily, before bedtime, over a period of ten weeks.

The study was double-blind, meaning that neither the participants nor the researchers directly monitoring the patients knew who was receiving the medication and who was receiving a placebo. This strategy reduces the possibility that the expectations of either the participants or the researchers could influence the results.

The amount of dronabinol administered was not the same for everyone. Participants began with a low dose, ranging from 2.5 to 15 milligrams, which could vary depending on the specific treatment regimen. To determine whether the medication was effective, the researchers assessed the participants' nightmares both before the study began and again after ten weeks, using a clinical scale specifically designed for post-traumatic stress disorder.

One of the items on this scale measures the frequency and intensity of the nightmares. Consequently, rather than simply asking whether a person felt “better,” the researchers had a standardized method for comparing the intensity of symptoms before and after the treatment.

After ten weeks, participants who received dronabinol showed a greater reduction in the frequency and intensity of nightmares compared to those who received a placebo. The difference between the two groups was statistically significant, indicating that, within the scope of this study, the improvement observed with dronabinol was greater than that observed with the placebo. The magnitude of this difference was also considered relevant by the researchers.

In other words, the results suggest that THC, administered in the form of dronabinol, may have a specific effect on nightmares related to post-traumatic stress disorder.

However, the study also identified an important issue regarding safety. Adverse effects, that is, unwanted effects occurring during treatment, were experienced by 89.7% of the individuals who received dronabinol and 77.1% of those who received the placebo. Five participants in the dronabinol group discontinued treatment due to these effects, while six individuals in the placebo group did the same.

Furthermore, seven participants who received dronabinol experienced adverse events considered serious, whereas no such events occurred in the placebo group. The researchers more frequently observed mild to moderate side effects, such as dizziness, headache, or increased appetite.

Therefore, although the results indicate a reduction in nightmares, this does not mean that THC is a simple or suitable solution for everyone with post-traumatic stress disorder. The researchers themselves emphasize that larger studies are still needed, specifically, studies that follow patients over a longer period, to better understand the long-term benefits and risks of the treatment.

READ MORE:

Dronabinol for nightmares in post-traumatic stress disorder: a randomized controlled trial 

Stefan Roepke, Nikola Schoofs, Kathlen Priebe, Felix Wuelfing, Kristina Meyer, Astrid Gieselmann, Katharina Stieglbauer, Milagros Galve, Sarah Biedermann, Jürgen Gallinat, Ingo Schäfer, Christian Schmahl, Jenny Zähringer, Robert Roehle, Erin D. Sprünken, Tim Friede, Stefan M. Gold, Tolou Maslahati, Christian Otte, and Stefanie Koglin

Nature Medicine, volume 32, pages 3396–3405 (2026) 

DOI:10.1038/s41591-026-04546-9

Abstract: 

Nightmares are a hallmark of post-traumatic stress disorder (PTSD), yet pharmacological treatments remain limited. Here we conducted a multicenter, double-blind, randomized, placebo-controlled trial to evaluate the efficacy and safety of dronabinol (BX-1; Δ9-tetrahydrocannabinol (THC)) for PTSD-related nightmares. Adults with PTSD and recurrent nightmares were randomly assigned to receive dronabinol (2.5–15 mg) or placebo, once daily before bedtime, for 10 weeks. The primary endpoint was change from baseline to week 10 in the Clinician-Administered PTSD Scale for DSM-IV (CAPS-IV) B2 item assessing nightmare frequency and intensity. A total of 171 patients underwent randomization (mean age, 37.9 ± 12.8 years; 79.3% female), with 87 assigned to dronabinol and 84 to placebo. At week 10, reduction in CAPS-IV B2 scores was significantly greater with dronabinol than with placebo (between-group difference −1.50; 95% confidence interval −2.28 to −0.71; Cohen’s d = 0.65; P < 0.001). Adverse events occurred in 78 patients (89.7%) receiving dronabinol and 64 (77.1%) receiving placebo. Treatment discontinuation due to adverse events occurred in five (5.7%) and six (7.2%) patients, respectively. Serious adverse events occurred in seven patients (8.0%) receiving dronabinol and in none receiving placebo. This trial provides evidence that dronabinol reduces the frequency and intensity of PTSD-related nightmares, although long-term efficacy and safety require further evaluation. ClinicalTrials.gov: NCT04448808.