Possibly Effective for
- Multiple sclerosis (MS). A prescription-only nasal spray product (Sativex, GW Pharmaceuticals) containing both 9-delta-tetrahydrocannabinol (THC) and cannabidiol has been shown to be effective for improving pain, muscle-tightness, and urination frequency in people with MS. This product is used in over 25 countries outside of the United States. But there is inconsistent evidence on the effectiveness of cannabidiol for symptoms of multiple sclerosis when it is used alone. Some early research suggests that using a cannabidiol spray under the tongue might improve pain and muscle tightness, but not muscle spasms, tiredness, bladder control, mobility, or well-being and quality of life in patients with MS.
Insufficient Evidence for
- Bipolar disorder. Early reports suggest that taking cannabidiol daily does not improve manic episodes in people with bipolar disorders.
- A muscle disorder called dystonia. Early research suggests that taking cannabidiol daily for 6 weeks might improve dystonia by 20% to 50% in some people. But higher quality research is needed to confirm this.
- Epilepsy. Some early research suggests that taking cannabidiol daily for up to 18 weeks might reduce seizures in some people. But other research shows that taking cannabidiol daily for 6 months does not reduce seizures in people with epilepsy. Reasons for the conflicting data are unclear. Possibly the studies were too small.
- Huntington’s disease. Early research shows that taking cannabidiol daily does not improve Huntington’s disease symptoms.
- Insomnia. Early research suggests that taking cannabidiol 160 mg before bed improves sleep time in people with insomnia. But lower doses do not have this effect. Cannabidiol also does not seem to help people fall asleep and might reduce the ability to recall dreams.
- Parkinson’s disease. Some early research shows that taking cannabidiol daily for 4 weeks improves psychotic symptoms in people with Parkinson’s disease and psychosis. But taking a specific cannabis extract (Cannador) that contains THC and cannabidiol does not appear to improve involuntary muscle movements caused by the anti-Parkinson’s drug levodopa in people with Parkinson’s disease.
- Schizophrenia. Research on the use of cannabidiol for psychotic symptoms in people with schizophrenia is mixed. Some early research suggests that taking cannabidiol four times daily for 4 weeks improves psychotic symptoms and might be as effective as the antipsychotic medication amisulpride. But other early research suggests that taking cannabidiol for 14 days is not beneficial. The mixed results might be related to the cannabidiol dose used and duration of treatment.
- Quitting smoking. Early research suggests that inhaling cannabidiol with an inhaler for one week might reduce the number of cigarettes smoked by about 40% compared to baseline.
- Social anxiety disorder. Some early research shows that taking cannabidiol 300 mg daily does not improve anxiety in people with social anxiety disorder. But other early research suggests that taking a higher dose (400-600 mg) may improve anxiety associated with public speaking or medical imaging test in people with SAD.
- Other conditions.
More evidence is needed to rate the effectiveness of cannabidiol for these uses.