Clinical trials published in 2026 have continued to examine the potential therapeutic effects of marijuana and individual cannabinoids across a wide range of conditions, including insomnia, chronic pain, dementia, migraine, PTSD, fibromyalgia and cancer-related symptoms.
The studies below include randomized, placebo-controlled and crossover trials evaluating THC, CBD, CBN, whole-plant marijuana and cannabinoid-based formulations. All were published in peer-reviewed journals. Each section title links to The Marijuana Herald’s coverage of the study, which in turn links to the original research.
THC-CBD Formulation Reduced Agitation in Dementia Patients
In a multicenter Phase II clinical trial involving 120 hospice-eligible patients with Alzheimer’s disease or other forms of dementia, a purified THC-CBD formulation produced substantial reductions in agitation. Participants were randomly assigned to receive the cannabinoid formulation or placebo for 12 weeks. After two weeks, 83.9% of those receiving THC and CBD showed overall behavioral improvement, compared with 30.5% of the placebo group. By week 12, improvement was reported in 87.2% of the treatment group compared with 23.6% receiving placebo. Agitation scores also declined significantly more with THC-CBD treatment, while adverse-event rates were similar between the two groups.
THC Medication Significantly Reduced PTSD-Related Nightmares
A multicenter, randomized, double-blind, placebo-controlled clinical trial involving 171 adults with post-traumatic stress disorder found that dronabinol, a prescription form of THC, significantly reduced PTSD-related nightmares. Participants received either 2.5 to 15 milligrams of dronabinol or placebo nightly for 10 weeks. Nightmare scores declined by an average of 3.7 points in the THC group compared with 2.2 points with placebo, a statistically significant difference. More than one-third of patients receiving dronabinol reported no nightmares by the end of treatment, while another 21% experienced at least a 50% reduction. The benefits appeared primarily related to nightmares and sleep rather than overall PTSD or depression symptoms.
Cannabis-Based Herbal Formula Matched Lorazepam for Chronic Insomnia Relief
A Phase II randomized, double-blind, active-controlled clinical trial involving 100 adults with chronic insomnia found that a traditional Thai cannabis-based multi-herbal formulation performed at least as well as lorazepam for improving sleep quality. Eighty-two participants completed the four-week trial, with average sleep-quality scores reaching 3.44 in the herbal-formula group compared with 4.78 among those receiving lorazepam. The difference met the study’s predefined criteria for non-inferiority. Quality of life and stress also improved in both groups, and no clinically significant adverse effects were reported.
CBD Oil Was Well Tolerated in Dogs With Osteoarthritis
A randomized, double-blind, placebo-controlled crossover clinical trial involving 10 dogs with imaging-confirmed osteoarthritis found that oral CBD oil was well tolerated, although the small study did not establish a significant pain-relieving effect. Each dog received CBD for four weeks and placebo for four weeks, separated by a four-week washout period, allowing each animal to serve as its own control. Changes in several measures of pain and mobility were generally modest, with considerable variation between individual dogs. Only one dog experienced a treatment-related issue, mild diarrhea that resolved without intervention. Researchers said larger trials may be needed to reliably determine CBD’s effectiveness for osteoarthritis pain.
CBD Provided Pain Relief Comparable to Codeine-Acetaminophen After Eye Surgery
A randomized crossover clinical trial involving 35 adults found that oral CBD provided postoperative pain control comparable to codeine-acetaminophen following photorefractive keratectomy, a type of laser eye surgery. Participants underwent surgery on each eye separately, receiving 50 milligrams of CBD twice daily after one procedure and codeine-acetaminophen after the other. Researchers found no significant differences between the treatments in average or maximum pain levels, with recovery and visual outcomes also similar. CBD produced minimal side effects, and researchers concluded that it provided non-inferior pain relief and may have potential as an opioid-sparing option for acute postoperative pain.
Inhaled Marijuana Was Associated With Fewer Irregular Heartbeats
A randomized clinical trial involving 108 regular marijuana consumers found that days assigned to inhaled marijuana use were associated with fewer premature heartbeats than days assigned to abstinence. Participants wore continuous cardiac monitors during the 14-day crossover study and were randomly instructed each day to either use inhaled marijuana or abstain. Across more than 1,300 participant-days, marijuana use was associated with a 9% reduction in premature atrial and ventricular beats combined, driven primarily by a 10% reduction in premature atrial contractions. Premature ventricular contractions were not significantly affected.
THC-CBD Oil Reduced Use of Psychotropic Medications in Severe Dementia
A randomized, double-blind, placebo-controlled crossover trial involving 25 older adults with severe dementia found that THC-CBD oil significantly reduced their use of as-needed psychotropic medications. Participants received a cannabis oil containing THC and CBD in a 1:2 ratio for eight weeks, with doses reaching an average of 17.85 milligrams of THC and 35.7 milligrams of CBD per day. During cannabinoid treatment, participants received 64 administrations of as-needed medications such as antipsychotics and benzodiazepines, compared with 153 during placebo treatment. The oil was generally well tolerated, with no treatment-related serious adverse events. Six months later, patients who continued treatment remained on the oil, and 21% had discontinued all other psychotropic medications.
Full-Spectrum CBD Was Well Tolerated in Adults With HIV
A randomized, double-blind, placebo-controlled clinical trial involving 80 adults with long-term, virally suppressed HIV found that full-spectrum CBD was well tolerated and did not negatively affect liver or kidney function or key measures of HIV control. Participants received either CBD oil at 1 milligram per kilogram of body weight twice daily or placebo for 12 weeks, followed by four weeks of follow-up. Researchers found no meaningful differences in major liver and kidney markers, plasma viral load, HIV-DNA levels or CD4/CD8 ratios between the groups. The findings support the short-term safety and tolerability of full-spectrum CBD in adults receiving antiretroviral therapy.
High-Dose CBD Reduced Neuropathic Pain in Spinal Cord Injury Patients
A randomized, double-blind, placebo-controlled crossover trial involving 40 adults with spinal cord injuries found that high-dose CBD significantly reduced chronic neuropathic pain. Participants received CBD and placebo during separate six-week treatment periods, with CBD gradually increased to 800 milligrams per day. Average pain scores were 3.82 during CBD treatment compared with 4.36 with placebo. Nearly 38% of participants achieved at least a 30% reduction in pain while taking CBD, compared with 11.1% during placebo treatment. Researchers described the overall effect as statistically significant but modest, with adverse events generally minor.
Medical Cannabis Extracts Improved Cancer-Related Symptoms in About Half of Patients
A randomized, placebo-controlled, triple-blind clinical trial involving 89 cancer patients found that THC-dominant, CBD-dominant and balanced THC-CBD extracts improved cancer-related symptoms in about half of participants. Using an n-of-1 design in which each patient tested all three extracts and placebo, researchers found that 56% experienced a clinically meaningful improvement with at least one cannabis extract. Response rates reached 50% among patients primarily experiencing pain, 47% among those with sleep problems and 60% among those with anxiety. All three extracts performed significantly better than placebo overall, with improvements in sleep, anxiety and daytime tiredness contributing most to the benefit.
CBD Was Linked to Reduced Pain and Inflammation in Patients With Recurrent Pericarditis
A Phase II, open-label clinical trial involving 27 adults with recurrent pericarditis found that pharmaceutical CBD was associated with substantial reductions in chest pain and systemic inflammation. Average maximum pain scores declined from 5.8 at the beginning of treatment to 2.1 after eight weeks, with patients reaching a pain score of 2 or lower after a median of five days. Among 10 participants who began with elevated C-reactive protein, eight had normal levels by week eight. During an optional extension, 17 of 24 participants remained free of another recurrence while other pericarditis medications were tapered and discontinued. One participant experienced a serious adverse event that led to discontinuation of CBD.
CBN Improved Sleep Onset and Quality in Adults With Insomnia
A randomized, double-blind, placebo-controlled crossover clinical trial involving 20 adults with diagnosed insomnia found that 300 milligrams of cannabinol (CBN) improved several measures of sleep, although it did not significantly improve the study’s primary endpoint. Participants received single doses of 30 milligrams of CBN, 300 milligrams of CBN and placebo during separate treatment periods. The 300-milligram dose shortened the time needed to fall asleep, improved subjective sleep quality, increased stage 2 non-rapid eye movement sleep and reduced measures of nighttime arousal. However, neither dose significantly reduced wake time after sleep onset, the trial’s primary outcome.
CBD Suppositories Were Linked to Reduced Chronic Pelvic Pain Symptoms
A clinical trial involving 16 men with chronic nonbacterial prostatitis, also known as chronic pelvic pain syndrome, found that suppositories containing CBD and hyaluronic acid were associated with significant reductions in symptoms. Participants used a suppository containing 100 milligrams of CBD and 6.6 milligrams of hyaluronic acid nightly for 30 days. Median symptom scores fell from 24.5 to 20, with 81.3% of participants experiencing overall improvement. Urinary symptoms also improved, while changes in erectile function were not statistically significant. No adverse events were reported. The pilot trial did not include a placebo group.
THC-CBD Marijuana Oil May Reduce Pain and Improve Sleep in Fibromyalgia Patients
A randomized, double-blind, placebo-controlled trial involving 24 adults with fibromyalgia found that a marijuana oil containing equal amounts of THC and CBD was well tolerated and produced encouraging improvements in pain, sleep and overall fibromyalgia impact. After dose titration and 12 weeks of stable treatment, 70% of participants receiving THC-CBD oil reported at least a 30% reduction in pain, compared with 40% receiving placebo. Clinically meaningful improvement in overall fibromyalgia impact occurred in 40% of the marijuana group compared with 10% of the placebo group. No serious adverse events occurred, although researchers emphasized that the trial was primarily designed to assess feasibility and was too small to establish efficacy conclusively.
CBD With Terpenes May Reduce Anxiety and Parental Stress in Autistic Children
A randomized, double-blind, placebo-controlled crossover trial involving 29 autistic children ages 5 to 12 found that CBD oil containing terpenes improved several secondary measures, although it did not significantly improve the study’s primary measure of overall social responsiveness. Participants received weight-based CBD oil and placebo during separate 12-week periods. CBD was associated with improvements in anxiety and social relating, while parents reported significantly lower stress during the CBD treatment period. No significant improvement was observed in adaptive functioning, and the treatment was generally well tolerated, with mild gastrointestinal discomfort reported in two children.
THC and CBD Combination Was Significantly More Effective Than Placebo for Acute Migraine
A randomized, double-blind, placebo-controlled crossover clinical trial involving 92 adults with migraine found that vaporized marijuana containing both THC and CBD significantly improved acute migraine outcomes. Participants treated separate attacks with THC-dominant marijuana, CBD-dominant marijuana, a combination containing 6% THC and 11% CBD, or placebo. Two hours after treatment, 67.2% of attacks treated with the THC-CBD combination achieved pain relief, compared with 46.6% with placebo, while complete pain freedom occurred in 34.5% versus 15.5%. Benefits remained evident at 24 and 48 hours. THC alone improved pain relief but not all major outcomes, while CBD alone did not significantly outperform placebo. No serious adverse events were reported.
Cannabis Oil Matched Lorazepam for Insomnia and Improved Quality of Life
A randomized clinical trial involving 60 adults with chronic insomnia found that cannabis sativa oil produced sleep improvements comparable to lorazepam while producing larger improvements in quality of life. Participants were assigned to cannabis oil, a traditional Thai herbal treatment or lorazepam for four weeks. Average sleep-quality scores in the cannabis oil group fell from 13.6 to 5.1, compared with a decline from 14.4 to 5.8 in the lorazepam group, with no statistically significant difference between treatments. Quality-of-life improvements were greater with cannabis oil and the herbal remedy than with lorazepam. Adverse effects were mild, with no serious events reported.
CBD Reduced Anxiety and Perceived Effort in Runners
A randomized, placebo-controlled crossover clinical trial involving 12 recreational runners found that a single 300-milligram dose of CBD increased feelings of calm and relaxation and reduced perceived exertion during a two-mile run. Participants completed separate CBD and placebo sessions, serving as their own controls. CBD increased reported calmness by 21% and relaxation by 22%, while perceived exertion at the one-mile mark was 8% lower. CBD did not significantly affect overall running time, blood pressure, heart rate variability or gastrointestinal symptoms.
CBD Gel Reduced Jaw Muscle Activity in Adults With Temporomandibular Disorders
A randomized, double-blind pilot clinical trial involving 20 adults with temporomandibular disorders found that nightly use of intraoral CBD gel significantly reduced jaw muscle activity. Participants used either a CBD-only gel or CBD combined with halloysite for six weeks. Masseter muscle activity fell by roughly 38% on average in both groups, with some participants experiencing substantially larger reductions. No significant overall difference was found between the two formulations, and no adverse events were reported. The trial did not include a non-CBD placebo group.
THC-CBD Treatment Reduced Pain and Improved Jaw Function in Patients With Chronic TMD
A clinical study involving 20 adults with chronic temporomandibular disorder found that a balanced THC-CBD treatment significantly reduced pain and improved jaw function. Participants first completed a 90-day placebo period, followed by 90 days of sublingual THC and CBD in a 1:1 ratio, with doses gradually increased from 2 to 10 milligrams per day. Average pain scores fell from 7.35 to 3.50 during cannabinoid treatment, maximum mouth opening increased, and functional pain declined by roughly 90%. Placebo effects were minimal.
CBD Was Linked to Weight Gain in Women With Anorexia
A randomized, double-blind, placebo-controlled clinical trial involving 32 women with anorexia nervosa or atypical anorexia found that CBD was associated with a statistically significant increase in body mass index. Participants received CBD or placebo for 21 days, with the CBD dose gradually increased throughout treatment. Those receiving CBD experienced consistent weight gains, while the placebo group showed little change. Anxiety, depression and eating-disorder symptom changes were not statistically significant, although some measures of body-image concerns and perceived control over eating improved. CBD was generally well tolerated.
CBD Reduced Pain and Physical Limitations Following Exercise-Related Muscle Injury
A randomized, double-blind, placebo-controlled clinical trial involving 29 healthy adults found that CBD may reduce pain and improve recovery following experimentally induced muscle injury. Participants received a CBD-rich hemp extract containing 67 milligrams of CBD per day or placebo for 15 days, with a quadriceps injury protocol performed on day 10. At 48 hours after injury, the CBD group reported lower peak pain at rest and during movement, along with less strength loss and physical disability. No treatment-related adverse reactions were reported.
CBD Increased Blood THC Levels When Marijuana Was Vaporized
A randomized, double-blind, placebo-controlled human trial involving 48 adolescents and adults found that combining CBD with THC during vaporized marijuana use significantly increased THC exposure in the bloodstream. Participants completed sessions using THC alone, THC combined with CBD and placebo. When CBD was combined with THC, total THC exposure increased by roughly 75%, while peak blood THC levels were nearly twice as high as with THC alone. Researchers found no strong evidence that the pharmacokinetic effects differed between adolescents and adults.
CBD Did Not Outperform Placebo for Jaw Pain in Patients With Myofascial Pain Disorder
A randomized, double-blind, placebo-controlled clinical trial involving 54 adults with moderate to severe jaw pain found that oral CBD did not significantly reduce pain compared with a hemp seed oil placebo. Participants received CBD or placebo for three months, with pain and jaw function measured throughout treatment. Both groups experienced statistically significant improvements in jaw function over time, but pain scores remained similar between the groups and CBD showed no meaningful advantage over placebo. No major safety concerns were emphasized in the study.
Cannabinoid Capsules Were Linked to Pain Relief in Fibromyalgia and Arthritis Patients
A randomized clinical study involving adults with fibromyalgia, rheumatoid arthritis or osteoarthritis found that several cannabinoid formulations were associated with improvements in pain, mental health and physical functioning. Researchers recruited 276 participants and randomly assigned them to one of three cannabinoid capsule formulations for 12 weeks, with 168 completing all study questionnaires. Significant improvements were reported across nearly all measured outcomes except cognitive function. Most effects did not differ significantly by cannabinoid formulation or pain condition, although certain formulations produced different effects on sleep disturbance and neuropathic pain.
Full-Spectrum Cannabis Oil Reduced Anesthetic Needs in Dogs Undergoing Cancer Surgery
A randomized, placebo-controlled veterinary clinical trial involving 20 female dogs with mammary tumors found that full-spectrum cannabis oil containing THC and CBD substantially reduced the amount of anesthesia required during surgery. Dogs received cannabis oil or placebo for seven days before surgery, with an additional dose given before anesthesia. Those receiving cannabis needed 2.33 milligrams per kilogram of propofol to induce anesthesia, compared with 5.98 milligrams per kilogram in the placebo group, representing a 61% anesthetic-sparing effect. No adverse events were reported during treatment or immediately after anesthesia.
High-Dose CBD Increased Testosterone Levels in Men
A randomized, placebo-controlled crossover study involving 12 healthy adults found that short-term, high-dose CBD significantly increased testosterone levels among male participants and altered several other steroid hormones. Participants received placebo or 750 milligrams of CBD twice daily for three days, followed by another 750-milligram dose on day four. Testosterone levels among men were 1.44 times higher following CBD than placebo, although levels remained within normal physiological ranges. CBD was also associated with changes in progesterone-related hormones, cortisol and corticosterone. Researchers said the clinical significance of the hormonal changes remains unclear.
THC-CBD Treatment Reduced Restless Legs Syndrome Severity
A prospective, open-label study involving 18 patients with restless legs syndrome found that a formulation containing 2.7 milligrams of THC and 2.5 milligrams of CBD significantly reduced symptom severity. Average scores on the International Restless Legs Syndrome Rating Scale improved after one and three months of treatment, while time spent awake after initially falling asleep also declined significantly. After one year, two-thirds of participants remained on treatment and continued to show improvement. The study was limited by its small size, lack of placebo control and open-label design.
Full-Spectrum CBD Oil Reduced Pain From Burning Mouth Syndrome
A placebo-controlled clinical trial involving 26 adults with burning mouth syndrome found that full-spectrum CBD oil significantly reduced pain and improved oral health-related quality of life. Participants received CBD or an avocado seed oil placebo, with CBD doses ranging from 10 to 50 milligrams per day. By the final assessment, median pain scores among CBD patients had fallen to zero on a 10-point scale, compared with more than six in the placebo group. No serious adverse events occurred, although one participant discontinued treatment following headache, dizziness and weakness.
CBD Enema Was Linked to Improved Symptoms in Patients With Ulcerative Proctitis
An open-label pilot clinical study involving 14 adults with treatment-resistant ulcerative proctitis found that a daily enema containing 60 milligrams of CBD and sodium propionate was associated with significant improvements in disease activity, pain, bleeding and stool frequency. Half of all participants achieved the study’s primary endpoint, rising to 77% among those who completed the full 12-week treatment period. Five of nine completers reached clinical remission. The treatment was generally well tolerated, but the small study lacked a placebo group, preventing researchers from establishing that CBD caused the improvements.
Men and Women Experienced Similar Effects From Smoked Marijuana Across THC Potencies
A randomized, double-blind, placebo-controlled clinical trial involving 35 adults found little evidence of consistent differences between men and women in the acute effects of smoked marijuana. Participants completed sessions using placebo marijuana and marijuana containing 6.25%, 12.5% and 22% THC. Men and women reached similar blood concentrations of THC and generally experienced similar effects on feeling high, mood and cognition, although women smoked for longer and had lower oral-fluid THC concentrations. Researchers said larger studies are needed to examine possible hormonal and other sex-related differences.
