Cannabidiol is a chemical in the Cannabis sativa plant, also known as marijuana or hemp. Over 80 chemicals, known as cannabinoids, have been identified in the Cannabis sativa plant. While delta-9-tetrahydrocannabinol (THC) is the major active ingredient in marijuana, cannabidiol is also obtained from hemp, which contains only very small amounts of THC.
The passage of the 2018 Farm Bill made it legal to sell hemp and hemp products in the U.S. But that doesn't mean that all hemp-derived cannabidiol products are legal. Since cannabidiol has been studied as a new drug, it can't be legally included in foods or dietary supplements. Also, cannabidiol can't be included in products marketed with therapeutic claims. Cannabidiol can only be included in "cosmetic" products and only if it contains less than 0.3% THC. But there are still products labeled as dietary supplements on the market that contain cannabidiol. The amount of cannabidiol contained in these products is not always reported accurately on the product label.
Cannabidiol is most commonly used for seizure disorder (epilepsy). It is also used for anxiety, pain, a muscle disorder called dystonia, Parkinson disease, Crohn disease, and many other conditions, but there is no good scientific evidence to support these uses.
How does it work?
Cannabidiol has effects on the brain. The exact cause for these effects is not clear. However, cannabidiol seems to prevent the breakdown of a chemical in the brain that affects pain, mood, and mental function. Preventing the breakdown of this chemical and increasing its levels in the blood seems to reduce psychotic symptoms associated with conditions such as schizophrenia. Cannabidiol might also block some of the psychoactive effects of delta-9-tetrahydrocannabinol (THC). Also, cannabidiol seems to reduce pain and anxiety.
Uses & Effectiveness
Likely Effective for
Seizure disorder (epilepsy). A specific cannabidiol product (Epidiolex, GW Pharmaceuticals) has been shown to reduce seizures in adults and children with various conditions that are linked with seizures. This product is a prescription drug for treating seizures caused by Dravet syndrome, Lennox-Gastaut syndrome, or tuberous sclerosis complex. It has also been shown to reduce seizures in people with Sturge-Weber syndrome, febrile infection-related epilepsy syndrome (FIRES), and specific genetic disorders that cause epileptic encephalopathy. But it's not approved for treating these other types of seizures. This product is usually taken in combination with conventional anti-seizure medicines. Some cannabidiol products that are made in a lab are also being studied for epilepsy. But research is limited, and none of these products are approved as prescription drugs.
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
A type of inflammatory bowel disease (Crohn disease). Early research shows that taking cannabidiol does not reduce disease activity in adults with Crohn disease.
Diabetes. Early research shows that taking cannabidiol does not improve blood glucose control adults with type 2 diabetes.
A movement disorder marked by involuntary muscle contractions (dystonia). It is unclear if cannabidiol is beneficial for dystonia.
An inherited condition marked by learning disabilities (fragile- X syndrome). Early research suggests that applying cannabidiol gel might reduce anxiety and improve behaviour in children with fragile X syndrome.
A condition in which a transplant attacks the body (graft-versus-host disease or GVHD). Graft-versus-host disease is a complication that can occur after a bone marrow transplant. Early research has found that taking cannabidiol daily starting 7 days before bone marrow transplant and continuing for 30 days after transplant can extend the time it takes for a person to develop GVHD.
An inherited brain disorder that affects movements, emotions, and thinking (Huntington disease). Early research shows that taking cannabidiol daily does not improve symptoms of Huntington disease.
Multiple sclerosis (MS). Early research suggests that using a cannabidiol spray under the tongue might improve pain and muscle tightness in people with MS.
Withdrawal from heroin, morphine, and other opioid drugs. Early research shows that taking cannabidiol for 3 days might reduce cravings and anxiety in people with heroin use disorder.
Parkinson disease. Early research shows that cannabidiol might reduce anxiety and psychotic symptoms in people with Parkinson disease.
Schizophrenia. Early research suggests that taking cannabidiol improves symptoms and wellbeing in people with schizophrenia.
Quitting smoking. Early research suggests that inhaling cannabidiol with an inhaler for one week might reduce the number of cigarettes smoked by smokers trying to quit.
A type of anxiety marked by fear in some or all social settings (social anxiety disorder). Early research shows that cannabidiol might improve anxiety in people with this disorder. But it's unclear if it helps reduce anxiety during public speaking.
A group of painful conditions that affect the jaw joint and muscle (temporomandibular disorders or TMD). Early research shows that applying an oil containing cannabidiol to the skin might reduce pain in people with TMD.
Nerve damage in the hands and feet (peripheral neuropathy).
Bipolar disorder.
Insomnia.
Other conditions.
More evidence is needed to rate the effectiveness of cannabidiol for these uses.
Side Effects & Safety
When taken by mouth: Cannabidiol is POSSIBLY SAFE when taken by mouth or sprayed under the tongue appropriately. Cannabidiol in doses of up to 300 mg daily have been taken by mouth safely for up to 6 months. Higher doses of 1200-1500 mg daily have been taken by mouth safely for up to 4 weeks. A prescription cannabidiol product (Epidiolex) is approved to be taken by mouth in doses of up to 25 mg/kg daily. Cannabidiol sprays that are applied under the tongue have been used in doses of 2.5 mg for up to 2 weeks.
Some reported side effects of cannabidiol include dry mouth, low blood pressure, light headedness, and drowsiness. Signs of liver injury have also been reported in some patients, but this is less common.
When applied to the skin: There isn't enough reliable information to know if cannabidiol is safe or what the side effects might be.
Special Precautions & Warnings:
Pregnancy and breast-feeding: Cannabidiol is POSSIBLY UNSAFE to use if you are pregnant or breast feeding. Cannabidiol products can be contaminated with other ingredients that may be harmful to the fetus or infant. Stay on the safe side and avoid use.
Children: A prescription cannabidiol product (Epidiolex) is POSSIBLY SAFE when taken by mouth in doses up to 25 mg/kg daily. This product is approved for use in certain children 1 year of age and older.
Liver disease: People with liver disease may need to use lower doses of cannabidiol compared to healthy patients.
Parkinson disease: Some early research suggests that taking high doses of cannabidiol might make muscle movement and tremors worse in some people with Parkinson disease.
Dosing
The following doses have been studied in scientific research: ADULTS BY MOUTH:
For epilepsy: A prescription cannabidiol product (Epidiolex) has been used. The recommended starting dose for Lennox-Gastaut syndrome and Dravet syndrome is 2.5 mg/kg twice daily (5 mg/kg/day). After one week the dose can be increased to 5 mg/kg twice daily (10 mg/kg/day). If the person doesn't respond to this dose, the maximum recommended is 10 mg/kg twice daily (20 mg/kg/day). The recommended starting dose for tuberous sclerosis complex is 2.5 mg/kg twice daily (5 mg/kg/day). This can be increased at weekly intervals if necessary, up to a maximum of 12.5 mg/kg twice daily (25 mg/kg/day). There is no strong scientific evidence that nonprescription cannabidiol products are beneficial for epilepsy.
CHILDREN
BY MOUTH:
For epilepsy: A prescription cannabidiol product (Epidiolex) has been used. The recommended starting dose for Lennox-Gastaut syndrome and Dravet syndrome is 2.5 mg/kg twice daily (5 mg/kg/day). After one week the dose can be increased to 5 mg/kg twice daily (10 mg/kg/day). If the person doesn't respond to this dose, the maximum recommended is 10 mg/kg twice daily (20 mg/kg/day). The recommended starting dose for tuberous sclerosis complex is 2.5 mg/kg twice daily (5 mg/kg/day). This can be increased at weekly intervals if necessary, up to a maximum of 12.5 mg/kg twice daily (25 mg/kg/day). There is no strong scientific evidence that nonprescription cannabidiol products are beneficial for epilepsy.
