In recent years, the U.S. market — from the internet to your local strip mall — has seen an explosion of products based on cannabidiol, or CBD, as it's better known.
CBD is one of the two most active ingredients found in the plant Cannabis sativa. The other is tetrahydrocannabinol (THC), the part of the plant that changes your mental state, commonly called “getting high.” CBD does not get you high, but it is an active ingredient. Both CBD and THC are known as cannabinoids.
The uses, benefits and side effects of CBD are being studied. So far, though, there have not been enough high-quality studies in humans for government regulators to approve any medical use for CBD other than treatment for some rare types of epilepsy in children.
Is CBD legal?
All products of Cannabis sativa are called cannabis. Cannabis with high levels of THC is marijuana, and cannabis with less than 0.3 percent THC is defined by the U.S. Food and Drug Administration (FDA) as hemp. The 2018 Farm Bill removed hemp as an FDA-controlled substance. That has increased the availability of CBD as a hemp product, but it still remains in somewhat of a legal gray zone.
According to FDA regulation, CBD cannot be used in a diet supplement that is sold across state lines. In-state use is subject to state laws, and those vary from state to state. Also, CBD cannot be included in products marketed with any therapeutic claims. For consumers, that means you have to check your state's laws to find out if a CBD product is restricted in your state.
Uses of CBD
CBD is being used to treat anxiety and insomnia, with some studies supporting the use of CBD to help people with insomnia fall asleep and stay asleep longer, according to Harvard Medical School's Harvard Health blog. Though some studies done on animals have produced support for CBD as a treatment for chronic pain, Harvard Health notes that more human studies would be needed to support this use among people. According to the Arthritis Foundation, some people with arthritis are using CBD to reduce pain and swelling of their joints, but this use is also not yet supported by human studies.
Nonetheless — and despite FDA warnings — some CBD products are being marketed with unproven claims. They're marketed as drugs, food additives, supplements, cosmetic products and even pet medicines. The Federal Trade Commission has warned manufacturers to stop selling CBD products that claim to prevent or treat serious diseases, including cancer, Alzheimer’s disease, psychiatric conditions and diabetes.
Research on the benefits of CBD
The Natural Medicines Comprehensive Database rates the effectiveness of natural medicines, like CBD, based on the available scientific research. Their ratings can range from ineffective, through possibly effective and all the way up to effective. They also have a category called Insufficient Evidence to Rate. To date, that's where almost all the benefits of CBD fall.
The National Center for Complementary and Integrative Health also has a summary on the benefits of cannabinoids. Both of these organizations agree that, for now, the only proven benefit for CBD is the prescription medication Epidiolex. This is a purified form of CBD used to treat seizures in children that do not respond to other seizure medications.
There is, however, a long list of conditions for which CBD treatment might be beneficial. According to the U.S. National Library of Medicine, all possible benefits are based on early or unconfirmed research and would need to be confirmed in large, well-controlled human studies. Conditions that might benefit include:
- Dystonia. This is a movement disorder that causes unwanted muscle spasms. Early research suggests that taking CBD for 6 weeks may improve dystonia by up to 50 percent.
- Fragile X syndrome. This is an inherited condition that may be associated with anxiety. Early research found that CBD may reduce anxiety for some people with this syndrome.
- Graft-versus-host disease (GVHD). This is a complication that can occur after a bone marrow transplant. Early research suggests that taking CBD before and after a bone marrow transplant might delay the onset of GVHD.
- Insomnia. Early research suggests that taking CBD at bedtime may increase sleep time.
- Multiple sclerosis (MS). Early research has found that CBD might improve pain and muscle tightness for some people with MS. CBD has shown no benefits for other MS symptoms.
- Opioid withdrawal symptoms. Early research found that people have less craving and anxiety when withdrawing from opioid drugs after taking CBD for three days.
- Parkinson’s disease. Taking CBD daily for 4 weeks may improve the mental condition called psychosis that some people with Parkinson’s disease experience.
- Schizophrenia. Taking CBD four times each day for four weeks improved symptoms in one study, but another study did not find improvement.
- Anxiety. Early research has found that taking CBD may reduce anxiety associated with public speaking.
Research into other conditions has failed to show any CBD benefits. This does not mean that future studies will not find any benefits, but it may make it less likely that researchers will look. These conditions include bipolar disorder, Crohn’s disease, diabetes and Huntington’s disease.
According to the National Cancer Institute, there are no studies that support or suggest the need for further research into using CBD to treat cancer.
There have been many studies on CBD for pain relief, but these have studied cannabis as a combination of CBD and THC. A 2018 review of 47 studies using cannabis or cannabinoids found a small benefit for people with chronic pain. About 30 percent of people in these studies got about a 30 percent reduction in pain. However, 26 percent of people taking a placebo also reported pain relief. The review concluded that the difference between the cannabinoids and placebo was too small to be significant.
Is CBD safe?
When the FDA approved the epilepsy drug Epidiolex, it was evaluated for safety as well as effectiveness. This evaluation points to three possible safety concerns:
- Side effects. Side effects that have been reported for CBD include diarrhea, sleepiness, dry mouth, dizziness, nausea, fatigue and irritability.
- Liver damage: This may occur with high doses.
- Interactions with other medications: Several drugs can be affected by CBD, especially drugs that are changed or broken down (metabolized) in your liver. CBD may also interact with the blood thinner warfarin (Coumadin). If you are taking any medication that has a side effect of drowsiness, CBD may make that effect worse.
According to the National Institutes of Health, CBD may be safe when taken by mouth at doses up to 300 milligrams (mg) a day for up to 6 months or at up to 1500 mg daily for up to 4 weeks. However, because CBD products are not regulated, you may not know how much you're actually getting. A 2017 review of 84 CBD products found that more than 40 percent contained significantly more CBD than stated on the label.
CBD may also be applied to the skin. However, it's not known how much CBD is absorbed through the skin or even if any CBD passes through the skin so there is no safety information available on CBD skin products.
One way not to take CBD is by inhaling it while vaping. The FDA warns that this may cause severe lung disease.
CBD also is not considered safe for women who are pregnant or breastfeeding at any dose. In addition to a lack of safety information on CBD for pregnancy or breastfeeding, there may be other ingredients in CBD that are unsafe for an infant or fetus.
If you have any type of liver disease, even a lower dose of CBD may cause liver damage.
The bottom line
If you check with your doctor first, and you are not at risk for any drug reactions or liver damage, taking CBD orally or topically may be safe. On the other hand, there are no proven benefits for any CBD products with the exception of the prescription medication Epidiolex. There are some known risks, and there may be some unknown risks. Taking CBD as a substitute for proven medical care from a health care provider is another potential risk. You might consider waiting for more research before assuming that any benefit from CBD will outweigh these risks.
- CDC, What You Need to Know (And What We’re Working to Find Out) About Products Containing Cannabis or Cannabis-derived Compounds, Including CBD, https://www.fda.gov/consumers/consumer-updates/what-you-need-know-and-what-were-working-find-out-about-products-containing-cannabis-or-cannabis
- NIH, NCCIH, Cannabis (Marijuana) and Cannabinoids: What You Need To Know, https://nccih.nih.gov/health/marijuana-cannabinoids
- Harvard Medical School, Cannabidiol (CBD) — what we know and what we don’t, https://www.health.harvard.edu/blog/cannabidiol-cbd-what-we-know-and-what-we-dont-2018082414476
- NIH, US National Library of Medicine, Cannabidiol (CBD), https://medlineplus.gov/druginfo/natural/1439.html
- Arthritis foundation, CBD for Arthritis Pain: What You Should Know, https://www.arthritis.org/health-wellness/healthy-living/managing-pain/pain-relief-solutions/cbd-for-arthritis-pain
- National Cancer Institute, Cannabis and Cannabinoids (PDQ), https://www.cancer.gov/about-cancer/treatment/cam/patient/cannabis-pdq
- Serious Health Claims for CBD Products Need Proof, FTC, 2019. https://www.consumer.ftc.gov/blog/2019/09/serious-health-claims-cbd-products-need-proof