Cannabinoids and Neurological Conditions: Epilepsy, Spasticity and Other Research

Neurological Research: how to read it

This page covers cannabinoids in conditions of the nervous system. It is education only and not advice to treat a condition with cannabis or CBD. Evidence labels: approved medicine, established, promising but limited, mixed, insufficient evidence and marketing claim. A study of a prescription CBD medicine does not apply to a store product.

Epilepsy

Approved medicine and established for specific syndromes. Epidiolex (purified CBD) is FDA-approved for seizures with Lennox-Gastaut syndrome, Dravet syndrome and tuberous sclerosis complex, age 1 and older. [1] In the EU, Epidyolex is authorized for the same conditions from age two; trials showed fewer seizures when added to other epilepsy medicines. [2]

What systematic reviews say:

• A 2025 meta-analysis of seven randomized trials found that CBD probably increased the number of people with at least a 50% fall in monthly seizures, and probably increased serious adverse events too. [3] It added that for most other comparisons and outcomes the effects were uncertain. [3]
• A 2023 BMJ umbrella review concluded that cannabidiol is effective in people with epilepsy. [4] The BMC 2022 review found a significant CBD effect for epilepsy. [5]
• An older Cochrane review (2014), written before Epidiolex was approved, said no reliable conclusions could be drawn. [6]
• For other, more common forms of epilepsy, NCCIH says not enough research exists to draw conclusions. [7]

Safety. The Epidiolex label warns of dose-related liver enzyme rises, more often in people taking valproate and clobazam. [1] Somnolence and sedation affected 32% of treated patients in studies versus 11% on placebo. [1] Epilepsy medicines as a group raise the risk of suicidal thoughts or behavior. [1] The BMJ review found CBD also increased pneumonia, gastrointestinal adverse events and somnolence. [4] The FDA says the liver risk can be managed under medical supervision with an approved product, but it is less clear how it is managed when CBD is used widely without supervision. [8]

In England, NICE recommends cannabidiol with clobazam for Lennox-Gastaut syndrome only if seizure frequency is checked and treatment stops when seizures have not fallen by at least 30%. [9]

Multiple sclerosis and spasticity

Spasticity means muscle stiffness and spasms. Mixed: patients often report improvement, objective tests show less. NCCIH summarized a review of 17 studies that found a small improvement in patient-rated spasticity, pain and bladder problems, but no significant improvement in spasticity on objective tests. [7]

A 2024 review of 31 studies, with six randomized trials, found that nabiximols was the most common product used and reported it was effective for MS spasticity. [10] The results varied widely between studies (a measure of inconsistency of 97%), and most included studies were not randomized, so we rate this as promising but limited. [10]

Regulators: The NHS says nabiximols (Sativex) is licensed in the UK for adults with MS-related muscle spasticity that has not improved with other treatments. [11] NICE advises a 4-week trial in eligible adults with moderate to severe spasticity. [9] Nabiximols is not approved in the US. [7] See approved cannabinoid medicines.

Parkinson's disease

Mixed. A 2026 meta-analysis of randomized trials found 11 RCTs, six eligible for pooling, and concluded cannabinoids have not shown significant benefit, while urging caution in interpretation. [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 these are mostly small trials. The FDA has also warned a company over unsubstantiated claims about CBD for Parkinson's and Alzheimer's disease. [14]

Anxiety and mental health

Insufficient evidence. NCCIH describes one study of 24 people with social anxiety disorder who had less anxiety in a simulated public speaking test after CBD than after placebo. [7] A 2019 systematic review found scarce evidence that cannabinoids improve depression, anxiety and ADHD. [15] It found very low quality evidence that pharmaceutical THC, with or without CBD, gave a small improvement in anxiety in people with other medical conditions. [15] Read more at anxiety disorders and CBT for anxiety and stress.

Other conditions

Proper evidence not found in the sources we read for CBD or cannabis in autism, Alzheimer's disease or dementia, and the FDA has warned a company about unsubstantiated claims for autism, ADHD, Parkinson's and Alzheimer's disease. [14] Those are marketing claims. We searched FDA, NCCIH, NICE, NHS and PubMed reviews on epilepsy, MS, Parkinson's and mental disorders only.

Before considering any cannabinoid

Talk to the clinician who manages your condition. CBD can cause liver injury and can change how other medicines work, and the FDA lists drowsiness, diarrhea and mood changes among side effects. [8] See cannabis and CBD medicine interactions, CBD and liver safety. Laws differ by country and change; this is not legal advice.