Cannabidiol (CBD): What we know and what we don t

There is a lot we do not know about CBD. Currently, we do not know how CBD use affects a person over time. We also do not know how different modes of CBD use (smoking, vaping, eating, applying to skin, etc.) affect a person.

CBD: What You Need to Know

woman holding bottle with CBD oil in hemp field

CBD can be derived from hemp or from non-hemp plants. Hemp is defined as any part of the cannabis sativa plant with no more than 0.3% of tetrahydrocannabinol (THC), the mind-altering substance in marijuana.

CBD Use in the United States

In 2018, the U.S. Congress passed and signed into law the Agriculture Improvement Act . This law removed hemp from the federal Controlled Substances Act, effectively legalizing CBD if it comes from hemp. 2 However, a few states have not removed hemp from their state’s controlled substances acts, so legality of CBD products differs across states.

CBD is marketed in many consumer products:

How Can CBD Affect Your Health?

Is CBD a medicine?

Scientists are still learning about how CBD affects the body. The U.S. Food and Drug Administration (FDA) approved Epidiolex, a medicine that contains purified CBD from hemp, to help treat rare seizure disorders. The FDA has concluded that this drug is safe and effective for this intended use. However, other marketed products and uses of CBD may not be FDA approved.

Potential harms and side effects

Using CBD products is not risk free. The FDA has limited data on CBD safety. Please consider these possible side effects and risks before using CBD: 3

  • Liver damage
  • Interference with other drugs you are taking, which may lead to injury or serious side effects
  • Drowsiness or sleepiness
  • Diarrhea or changes in appetite
  • Changes in mood, such as irritability

Using CBD during pregnancy is not recommended.

CBD use during pregnancy is not recommended. The potential health effects of using CBD products during pregnancy are currently unknown. In animals, high doses of CBD have caused negative effects on developing fetuses. 4

We do not know if CBD is passed to a baby through breast milk. Since negative effects have been associated with CBD use, people who are breastfeeding are encouraged to avoid CBD.

We do not know the effects of CBD on children’s developing brains. If you use products that contain CBD or THC, keep them in childproof containers and out of the reach of children.

For additional questions, contact your healthcare provider, your health department, or your local or regional poison control center at 1-800-222-1222, or 911 if it’s an emergency.

Unknowns

There is a lot we do not know about CBD. Currently, we do not know how CBD use affects a person over time. We also do not know how different modes of CBD use (smoking, vaping, eating, applying to skin, etc.) affect a person.

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Risk of Unintentional Poisoning

Many businesses that sell hemp and CBD products also sell products that contain THC. Individuals should be careful to not mistake THC products for hemp or CBD products. Products containing THC can result in psychoactive effects and adverse events. Additionally, most CBD products are not regulated by the FDA. As such, consumers should be aware that products labeled as hemp or CBD may contain other ingredients, such as THC, pesticides, heavy metals, bacteria, or fungi. 5

CDC released a Health Alert Network (HAN) Health Advisory in 2021 to inform consumers that CBD can be synthetically converted into Delta-8 THC, which is psychoactive and not well understood. This alert warns consumers about the potential for adverse events due to insufficient labeling of products containing THC and CBD.

If consumers experience adverse effects of THC- or CBD-containing products that are an immediate danger to their health, they should call their local or regional poison control center at 1-800-222-1222 or 911 or seek medical attention at their local emergency room and report the ingredients of products they have consumed to healthcare providers.

Learn more about CBD and Cannabis

  • Marijuana and Public Health
  • What We Know About Marijuana
  • Marijuana Use Disorder
  • Frequently Asked Questions
  • What CDC is Doing
  • What You Should Know About Using Cannabis, Including CBD, When Pregnant or Breastfeeding | FDA
  • State Medical Cannabis Laws (ncsl.org) | National Conference of State Legislatures
  • CDC Health Network Alert (HAN) Advisory: Increases in Availability of Cannabis Products Containing Delta-8 THC and Reported Cases of Adverse Events
  • What You Need to Know (And What We’re Working to Find Out) About Products Containing Cannabis or Cannabis-derived Compounds, Including CBD | FDA

References

  1. National Academies of Sciences, Engineering, and Medicine. The health effects of cannabis and cannabinoids: the current state of evidence and recommendations for research. Washington, DC: The National Academies Press; 2017.
  2. Agriculture Improvement Act of 2018. H.R.2, 115th Cong. 2017-2018.
  3. Federal Drug Administration. What You Need to Know (And What We’re Working to Find Out) About Products Containing Cannabis or Cannabis-derived Compounds, Including CBD. Consumer Updates. 2020.
  4. Huestis MA, Solimini R, Pichini S, Pacifici R, Carlier J, Busardò FP. Cannabidiol Adverse Effects and Toxicity. Curr Neuropharmacol. 2019;17(10):974-989.
  5. Federal Drug Administration. What You Should Know About Using Cannabis, Including CBD, When Pregnant or Breastfeeding. 2019.

Cannabidiol (CBD): What we know and what we don’t

cannabidiol

Cannabidiol (CBD) is often covered in the media, and you may see it touted as an add-in booster to your post-workout smoothie or morning coffee. You can even buy a CBD-infused sports bra. But what exactly is CBD? And why is it so popular?

How is cannabidiol different from marijuana, cannabis and hemp?

CBD, or cannabidiol, is the second most prevalent active ingredient in cannabis (marijuana). While CBD is an essential component of medical marijuana, it is derived directly from the hemp plant, a cousin of marijuana, or manufactured in a laboratory. One of hundreds of components in marijuana, CBD does not cause a “high” by itself. According to a report from the World Health Organization, “In humans, CBD exhibits no effects indicative of any abuse or dependence potential…. To date, there is no evidence of public health related problems associated with the use of pure CBD.”

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Is cannabidiol legal?

CBD is readily obtainable in most parts of the United States, though its exact legal status has been in flux. All 50 states have laws legalizing CBD with varying degrees of restriction. In December 2015, the FDA eased the regulatory requirements to allow researchers to conduct CBD trials. In 2018, the Farm Bill made hemp legal in the United States, making it virtually impossible to keep CBD illegal – that would be like making oranges legal, but keeping orange juice illegal.

The Farm Bill removed all hemp-derived products, including CBD, from the Controlled Substances Act, which criminalizes the possession of drugs. In essence, this means that CBD is legal if it comes from hemp, but not if it comes from cannabis (marijuana) – even though it is the exact same molecule. Currently, many people obtain CBD online without a medical marijuana license, which is legal in most states.

The evidence for cannabidiol health benefits

CBD has been touted for a wide variety of health issues, but the strongest scientific evidence is for its effectiveness in treating some of the cruelest childhood epilepsy syndromes, such as Dravet syndrome and Lennox-Gastaut syndrome (LGS), which typically don’t respond to antiseizure medications. In numerous studies, CBD was able to reduce the number of seizures, and, in some cases, stop them altogether. Epidiolex, which contains CBD, is the first cannabis-derived medicine approved by the FDA for these conditions.

Animal studies, and self-reports or research in humans, suggest CBD may also help with:

  • Anxiety Studies and clinical trials are exploring the common report that CBD can reduce anxiety.
  • Insomnia. Studies suggest that CBD may help with both falling asleep and staying asleep.
  • Chronic pain. Further human studies are needed to substantiate claims that CBD helps control pain. One animal study from the European Journal of Pain suggests CBD could help lower pain and inflammation due to arthritis when applied to skin. Other research identifies how CBD may inhibit inflammatory and neuropathic pain, which are difficult treat.
  • Addiction. CBD can help lower cravings for tobacco and heroin under certain conditions, according to some research in humans. Animal models of addiction suggest it may also help lessen cravings for alcohol, cannabis, opiates, and stimulants.

Is CBD safe?

Side effects of CBD include nausea, fatigue and irritability. CBD can increase the level of blood thinning and other medicines in your blood by competing for the liver enzymes that break down these drugs. Grapefruit has a similar effect with certain medicines.

People taking high doses of CBD may show abnormalities in liver related blood tests. Many non-prescription drugs, such as acetaminophen (Tylenol), have this same effect. So, you should let your doctor know if you are regularly using CBD.

A significant safety concern with CBD is that it is primarily marketed and sold as a supplement, not a medication. Currently, the FDA does not regulate the safety and purity of dietary supplements. So, you cannot be sure that the product you buy has active ingredients at the dose listed on the label. In addition, the product may contain other unknown elements. We also don’t know the most effective therapeutic dose of CBD for any particular medical condition.

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How can CBD be taken?

CBD comes in many forms, including oils, extracts, capsules, patches, vapes, and topical preparations for use on skin. If you’re hoping to reduce inflammation and relieve muscle and joint pain, a topical CBD-infused oil, lotion or cream – or even a bath bomb — may be the best option. Alternatively, a CBC patch or a tincture or spray designed to be placed under the tongue allows CBD to directly enter the bloodstream.

Outside of the US, the prescription drug Sativex, which uses CBD as an active ingredient, is approved for muscle spasticity associated with multiple sclerosis and for cancer pain. Within the US, Epidiolex is approved for certain types of epilepsy and tuberous sclerosis.

The bottom line on cannabidiol

Some CBD manufacturers have come under government scrutiny for wild, indefensible claims, such that CBD is a cure-all for cancer or COVID-19, which it is not. We need more research but CBD may prove to be a helpful, relatively non-toxic option for managing anxiety, insomnia, and chronic pain. Without sufficient high-quality evidence in human studies, we can’t pinpoint effective doses, and because CBD currently is typically available as an unregulated supplement, it’s hard to know exactly what you are getting.

If you decide to try CBD, make sure you are getting it from a reputable source. And talk with your doctor to make sure that it won’t affect any other medicines you take.

About the Author

photo of Peter Grinspoon, MD

Peter Grinspoon, MD , Contributor

Dr. Peter Grinspoon is a primary care physician, educator, and cannabis specialist at Massachusetts General Hospital; an instructor at Harvard Medical School; and a certified health and wellness coach. He is the author of the forthcoming book Seeing … See Full Bio

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