Cannabidiol (CBD) is a chemical in the Cannabis sativa plant, also known as cannabis or hemp. One specific form of CBD is approved as a drug in the U.S. for seizures.

Over 80 chemicals, known as cannabinoids, have been found in the Cannabis sativa plant. Delta-9-tetrahydrocannabinol (THC) is the most famous ingredient in cannabis. But CBD is obtained from hemp, a form of the Cannabis sativa plant that only contains small amounts of THC. CBD seems to have effects on some chemicals in the brain, but these are different than the effects of THC.

A prescription form of CBD is used for seizure disorder (epilepsy). CBD 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.

Laws passed in 2018 made it legal to sell hemp and hemp products in the US. But that doesn’t mean that all CBD products made from hemp are legal. Since CBD is an approved prescription drug, it can’t be legally included in foods or dietary supplements. CBD can only be included in “cosmetic” products. But there are still CBD products on the market that are labeled as dietary supplements. The amount of CBD contained in these products is not always the same as what is stated on the label.

Natural Medicines Comprehensive Database rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, Ineffective, and Insufficient Evidence to Rate.

The effectiveness ratings for CANNABIDIOL (CBD) are as follows:

Likely effective for…

• Seizure disorder (epilepsy). A specific prescription product (Epidiolex, GW Pharmaceuticals) is approved by the US FDA to treat seizures caused by Dravet syndrome, Lennox-Gastaut syndrome, or tuberous sclerosis complex. It is unclear if other forms of CBD are helpful for seizure. For now, stick with the prescription product.

There is interest in using CBD for a number of other purposes, but there isn’t enough reliable information to say whether it might be helpful for these uses.

When taken by mouth: CBD is possibly safe to take in appropriate doses. Doses of up to 200 mg daily have been used safely for up to 13 weeks. With the guidance of a healthcare provider, a specific prescription CBD product (Epidiolex) has been used at higher doses and for longer durations.

CBD can cause some side effects, such as dry mouth, low blood pressure, light headedness, and drowsiness. Signs of liver injury have also been reported with high doses of the prescription form of CBD, called Epidiolex.

When applied to the skin: There isn’t enough reliable information to know if CBD is safe or what the side effects might be.

Special precautions & warnings:

Pregnancy and breast-feeding: It may be unsafe to take CBD if you are pregnant or breast feeding. CBD 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: It is possibly safe for children to take a specific prescription CBD product (Epidiolex) by mouth in doses up to 25 mg/kg daily. This product is approved for use in children with certain conditions who are at least 1 year old. It isn’t clear if other CBD products are safe in children.

Liver disease: People with liver disease may need to use lower doses of CBD.

Parkinson disease: Some early research suggests that taking high doses of CBD might make muscle movement and tremors worse in some people with Parkinson disease.

Moderate

Be cautious with this combination.

Brivaracetam (Briviact)

Brivaracetam is changed and broken down by the body. CBD might decrease how quickly the body breaks down brivaracetam. This might increase levels of brivaracetam in the body.

Caffeine

Caffeine is changed and broken down by the body. CBD might decrease how quickly the body breaks down caffeine. This might increase levels of caffeine in the body.

Carbamazepine (Tegretol)

Carbamazepine is changed and broken down by the body. CBD might decrease how quickly the body breaks down carbamazepine. This might increase levels of carbamazepine in the body and increase its side effects.

Citalopram (Celexa)

Citalopram is changed and broken down by the body. CBD might decrease how quickly the body breaks down citalopram. This might increase levels of citalopram in the body and increase its side effects.

Clobazam (Onfi)

Clobazam is changed and broken down by the liver. CBD might decrease how quickly the liver breaks down clobazam. This might increase the effects and side effects of clobazam.

Eslicarbazepine (Aptiom)

Eslicarbazepine is changed and broken down by the body. CBD might decrease how quickly the body breaks down eslicarbazepine. This might increase levels of eslicarbazepine in the body by a small amount.

Everolimus (Zostress)

Everolimus is changed and broken down by the body. CBD might decrease how quickly the body breaks down everolimus. This might increase levels of everolimus in the body.

Lithium

Taking higher doses of CBD might increase levels of lithium. This can increase the risk of lithium toxicity.

Medications changed by the liver (Cytochrome P450 1A1 (CYP1A1) substrates)

Some medications are changed and broken down by the liver. CBD might change how quickly the liver breaks down these medications. This could change the effects and side effects of these medications.

Medications changed by the liver (Cytochrome P450 1A2 (CYP1A2) substrates)

Some medications are changed and broken down by the liver. CBD might change how quickly the liver breaks down these medications. This could change the effects and side effects of these medications.

Medications changed by the liver (Cytochrome P450 1B1 (CYP1B1) substrates)

Some medications are changed and broken down by the liver. CBD might change how quickly the liver breaks down these medications. This could change the effects and side effects of these medications.

Medications changed by the liver (Cytochrome P450 2A6 (CYP2A6) substrates)

Some medications are changed and broken down by the liver. CBD might change how quickly the liver breaks down these medications. This could change the effects and side effects of these medications.

Medications changed by the liver (Cytochrome P450 2B6 (CYP2B6) substrates)

Some medications are changed and broken down by the liver. CBD might change how quickly the liver breaks down these medications. This could change the effects and side effects of these medications.

Medications changed by the liver (Cytochrome P450 2C19 (CYP2C19) substrates)

Some medications are changed and broken down by the liver. CBD might change how quickly the liver breaks down these medications. This could change the effects and side effects of these medications.

Medications changed by the liver (Cytochrome P450 2C8 (CYP2C8) substrates)

Some medications are changed and broken down by the liver. CBD might change how quickly the liver breaks down these medications. This could change the effects and side effects of these medications.

Medications changed by the liver (Cytochrome P450 2C9 (CYP2C9) substrates)

Some medications are changed and broken down by the liver. CBD might change how quickly the liver breaks down these medications. This could change the effects and side effects of these medications.

Medications changed by the liver (Cytochrome P450 2D6 (CYP2D6) substrates)

Some medications are changed and broken down by the liver. CBD might change how quickly the liver breaks down these medications. This could change the effects and side effects of these medications.

Medications changed by the liver (Cytochrome P450 2E1 (CYP2E1) substrates)

Some medications are changed and broken down by the liver. CBD might change how quickly the liver breaks down these medications. This could change the effects and side effects of these medications.

Medications changed by the liver (Cytochrome P450 3A4 (CYP3A4) substrates)

Some medications are changed and broken down by the liver. CBD might change how quickly the liver breaks down these medications. This could change the effects and side effects of these medications.

Medications changed by the liver (Glucuronidated drugs)

Some medications are changed and broken down by the liver. CBD might change how quickly the liver breaks down these medications. This could change the effects and side effects of these medications.

Medications that decrease the breakdown of other medications by the liver (Cytochrome P450 2C19 (CYP2C19) inhibitors)

CBD is changed and broken down by the liver. Some drugs decrease how quickly the liver changes and breaks down CBD. This could change the effects and side effects of CBD.

Medications that decrease the breakdown of other medications in the liver (Cytochrome P450 3A4 (CYP3A4) inhibitors)

CBD is changed and broken down by the liver. Some drugs decrease how quickly the liver changes and breaks down CBD. This could change the effects and side effects of CBD.

Medications that increase breakdown of other medications by the liver (Cytochrome P450 3A4 (CYP3A4) inducers)

CBD is changed and broken down by the liver. Some drugs increase how quickly the liver changes and breaks down CBD. This could change the effects and side effects of CBD.

Medications that increase the breakdown of other medications by the liver (Cytochrome P450 2C19 (CYP2C19) inducers)

CBD is changed and broken down by the liver. Some drugs increase how quickly the liver changes and breaks down CBD. This could change the effects and side effects of CBD.

Methadone (Dolophine)

Methadone is broken down by the liver. CBD might decrease how quickly the liver breaks down methadone. Taking cannabidiol along with methadone might increase the effects and side effects of methadone.

Rufinamide (Banzel)

Rufinamide is changed and broken down by the body. CBD might decrease how quickly the body breaks down rufinamide. This might increase levels of rufinamide in the body by a small amount.

Sedative medications (CNS depressants)

CBD might cause sleepiness and slowed breathing. Some medications, called sedatives, can also cause sleepiness and slowed breathing. Taking CBD with sedative medications might cause breathing problems and/or too much sleepiness.

Sirolimus (Rapamune)

Sirolimus is changed and broken down by the body. CBD might decrease how quickly the body breaks down sirolimus. This might increase levels of sirolimus in the body.

Stiripentol (Diacomit)

Stiripentol is changed and broken down by the body. CBD might decrease how quickly the body breaks down stiripentol. This might increase levels of stiripentol in the body and increase its side effects.

Tacrolimus (Prograf)

Tacrolimus is changed and broken down by the body. CBD might decrease how quickly the body breaks down tacrolimus. This might increase levels of tacrolimus in the body.

Tamoxifen (Soltamox)

Tamoxifen is changed and broken down by the body. CBD might affect how quickly the body breaks down tamoxifen. This might affect levels of tamoxifen in the body.

Topiramate (Topamax)

Topiramate is changed and broken down by the body. CBD might decrease how quickly the body breaks down topiramate. This might increase levels of topiramate in the body by a small amount.

Valproate

Valproic acid can cause liver injury. Taking cannabidiol with valproic acid might increase the chance of liver injury. CBD and/or valproic acid might need to be stopped, or the dose might need to be reduced.

Warfarin

CBD might increase levels of warfarin, which can increase the risk for bleeding. CBD and/or warfarin might need to be stopped, or the dose might need to be reduced.

Zonisamide

Zonisamide is changed and broken down by the body. CBD might decrease how quickly the body breaks down zonisamide. This might increase levels of zonisamide in the body by a small amount.

Herbs and supplements with sedative properties

CBD might cause sleepiness and slowed breathing. Taking it along with other supplements with similar effects might cause too much sleepiness and/or slowed breathing in some people. Examples of supplements with this effect include hops, kava, L-tryptophan, melatonin, and valerian.

CBD can be taken with food or without food. But taking it with food can cause the body to absorb more CBD than when it is taken without food. This might increase the effects of CBD.

Fatty foods or drinks, such as whole milk, and alcohol can also make the body absorb more CBD.

CBD has most often been used by adults in doses of 200 mg or less per day. Speak with a healthcare provider to find out what dose might be best for a specific condition.

For information on using prescription CBD, a product called Epidiolex, speak with a healthcare provider.

2-[(1R,6R)-3-Methyl-6-prop-1-en-2-ylcyclohex-2-en-1-yl]-5-pentylbenzene-1,3-diol, CBD.

To learn more about how this article was written, please see the Natural Medicines Comprehensive Database methodology.

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