Cannabis sativa plant.
This plant, which contains more than 80 chemicals known as cannabinoids, is also called marijuana or hemp.
Two key ingredients in cannabis are tetrahydrocannabinol (THC) and CBD.
THC is responsible for the intoxicating effects of cannabis, and it might contribute to the plant's health benefits.
Unlike THC, CBD is not intoxicating.
Scientists believe that cannabinoids protect the cannabis plant itself from insects, bacteria, fungi, and environmental stressors.
CBD seems to prevent the breakdown of a chemical in the brain that helps control pain, mood, and mental function.
CBD is available in softgels, tablets, capsules, oils, gums, liquid extracts, and vape juice (for fillable electronic cigarettes).
Some of these products contain CBD only, and others contain CBD in combination with other ingredients.
The labels of many products containing CBD make inaccurate claims about the amount of CBD in the product, and CBD concentrations in the same product sometimes vary. For example, one study found that only 31% of CBD products were accurately labeled; 43% contained more CBD than indicated on the label and 26% contained less than was indicated on the label. Moreover, THC (or marijuana) was found in 21% of the products.
(See also Overview of Dietary Supplements.)
Claims for Cannabidiol
The only use of CBD generally recognized as safe and effective is treatment of certain seizure disorders. However, some people use CBD to treat many other health problems, including:
Bipolar disorder
Pain
Anxiety
Crohn disease
Diabetes
Sleep problems
Multiple sclerosis
Evidence for Cannabidiol
Three studies have shown that a pure CBD product, available by prescription only, reduces seizures in adults and children with 2 rare forms of epilepsy. In these studies, people were treated with the CBD product for 14 weeks while they continued to take other antiseizure medications. The CBD treatment decreased the numbers of seizures and reduced their frequency and severity.
Research on other health claims for CBD include studies in people that have been small and/or of poor quality.
In a small study, CBD seemed to reduce symptoms of anxiety and craving in abstinent people with heroin use disorder.
Another small study found that in people treated with antipsychotic medications for schizophrenia, CBD reduced symptoms of psychosis.
Several retrospective and observational studies suggest that CBD might have beneficial effects in certain conditions, including pain, anxiety, sleep problems, and colitis. But other evidence suggests that these benefits are modest, at best, and these studies have important limitations (for example, inconsistent results for different studies, no comparison with a placebo).
Side Effects of Cannabidiol
CBD is probably safe to take by mouth or sprayed under the tongue. But CBD can have side effects, such as dry mouth, low blood pressure, diarrhea, decreased appetite, mood changes, light-headedness, and sleepiness.
CBD can injure the liver, especially if it is not used under medical supervision.
The contaminants in some CBD products could harm fetuses or infants, so CBD might not be safe for women who are pregnant or breastfeeding.
People with liver disease who use CBD might need to take lower doses than healthy people.
High doses of CBD might make tremors and other unwanted movements worse in people with Parkinson disease.
In studies in animals, CBD decreased sperm growth and development and reduced testicle size, so it might affect fertility in men.
Some CBD products are contaminated with solvents, including some that can cause cancer, as well as pesticides, heavy metals, bacteria, and fungi. Some of these contaminants could be harmful to a fetus.
A synthetic product sold in Utah has caused some acute poisonings.
Drug Interactions with Cannabidiol
CBD could speed up or slow down the body's breakdown of certain medications and, therefore, decrease or increase levels of these medications in the body.
Examples of medications that may increase blood levels of CBD include the following:
CBD could interact in other ways with other medications, such as
Recommendations for Cannabidiol
A pure CBD product, available by prescription only, reduces the number of seizures as well as their severity and frequency in adults and children taking other antiseizure medications for one of 2 rare forms of epilepsy.
Other effects of CBD have not been confirmed in high-quality studies in people.
CBD can have side effects, such as dry mouth, low blood pressure, diarrhea, decreased appetite, mood changes, light-headedness, and sleepiness. However, serious side effects are rare, and CBD is probably safe for most people.
Pregnant and breastfeeding women and people with liver disease, Parkinson disease, and men who want to have children should not take CBD.
Taking CBD while taking other medications that can cause drowsiness or while drinking alcohol can cause extreme drowsiness, which could be dangerous.
The regulations about CBD are complicated and confusing. If a person chooses to take CBD, they should buy the product from a medical dispensary and look for a "Certificate of Authenticity."
More Information
The following English-language resource may be useful. Please note that THE MANUAL is not responsible for the content of this resource.
National Institutes of Health's National Center for Complementary and Integrative Health: Cannabis (Marijuana) and Cannabinoids: What You Need To Know
