Other Research Areas: PTSD, Appetite, Cancer Symptoms, Parkinson's, Arthritis and More

Post-traumatic stress disorder (PTSD)

Insufficient evidence, and a guideline recommends against. NCCIH says there has been little research on whether cannabis helps PTSD. In one very small study of 10 people, the synthetic cannabinoid nabilone was better than placebo for PTSD-related nightmares, and observational studies gave no clear answer. [1] A 2019 review found only one randomized trial (10 people) for PTSD. [2] A 2026 meta-analysis found no significant effects on PTSD outcomes, and a 2026 review found low-certainty evidence that THC-predominant cannabis may not improve PTSD. [3][4] The 2023 US Veterans Affairs and Department of Defense guideline recommends against cannabis or cannabis-derived products for PTSD and recommends specific psychotherapies and some medicines instead. [5] Read trauma and PTSD. If you are in crisis in the US, call or text 988.

Appetite and weight loss

Approved medicine for AIDS-related weight loss; otherwise mixed. Dronabinol is FDA-approved for adults with anorexia (loss of appetite) and weight loss from AIDS. [6] NCCIH says that approval rested mainly on a study of 139 people and that other studies were short and small, so evidence is limited. [1] A palliative-care review found cannabinoids beat placebo for weight gain and appetite in people with HIV but not in people with cancer. [7] In cancer, the National Cancer Institute reports that dronabinol did less than megestrol acetate in 469 adults with advanced cancer, and that a cannabis-extract trial in 243 patients found no appetite difference from placebo. [8] A 2022 review of cancer cachexia (wasting) found no significant benefit for appetite, weight or quality of life, from low-quality evidence. [9]

Cancer-related symptoms and cancer itself

The National Cancer Institute states the FDA has not approved cannabis as a treatment for cancer or any other medical condition, while dronabinol and nabilone are approved for treatment side effects. [8] The FDA has warned companies about unsubstantiated claims that CBD products treat cancer. [10] Label: marketing claim for cancer treatment; Proper evidence not found in the sources we read that cannabis treats cancer in people. For cancer pain, a 2023 Cochrane review found moderate-certainty evidence of no clinically relevant benefit from nabiximols and THC (see the chronic pain review). [11] For nausea, see chemotherapy nausea and vomiting.

Parkinson's disease

Mixed. A 2026 meta-analysis of randomized trials found 11 trials, six poolable, and no significant improvement in disease severity, motor examination or non-motor symptoms. It flagged a possible benefit signal for nabilone on non-motor symptoms that needs its own trials. [12] A 2023 systematic review of 13 studies instead reported that cannabis, CBD and nabilone consistently improved motor symptoms more than placebo. [13] The two disagree, and trials are small. The FDA has warned a company about unsubstantiated claims that CBD treats Parkinson's disease. [10]

Arthritis and joint pain

Insufficient evidence. The only rheumatoid arthritis review we read found three eligible studies (one randomized trial of 58 people on nabiximols) and judged evidence insufficient on efficacy and long-term safety. [14] For osteoarthritis, Proper evidence not found in the reviews we read. See acupuncture for knee osteoarthritis for a non-drug option.

Dementia

Insufficient evidence. A 2021 Cochrane review included four small trials (126 people) and said it could not be certain whether cannabinoids help or harm in dementia; any benefit might be too small to matter. [15] Sedation was more frequent with nabilone than placebo. [15] A 2024 overview described promising results with oral THC and CBD combinations in recent studies but said trials are still needed. [16] The FDA has warned a company over claims about Alzheimer's disease. [10]

Other conditions at a glance

1. Crohn's disease

   no good evidence of benefit

   3 studies, 93 people: no difference in remission versus placebo [1]

2. Ulcerative colitis

   insufficient evidence

   2 studies, 92 people: no remission difference with CBD capsules [1]

3. Irritable bowel syndrome

   insufficient evidence

   Little research; unknown whether helpful [1]

4. Tourette syndrome

   promising but limited

   2 small studies (36 people) suggested synthetic THC may reduce tics [1]

5. Glaucoma

   no good evidence of benefit

   Eye pressure fell briefly but less than existing treatments [1]

6. Autism, ADHD

   marketing claim

   FDA warned a company over unsubstantiated CBD claims [10]

Before considering any of this

The FDA lists liver injury, drowsiness, mood changes and medicine interactions as CBD risks. [17] A 2026 JAMA review says evidence is insufficient for most medical indications and that clinicians should check drug interactions and contraindications. [18] Read CBD medication interactions, cannabis clinical research overview and, for pain, sleep and anxiety, the pain, sleep and anxiety reviews. Epilepsy and MS are at epilepsy and multiple sclerosis.