Drugs That Should Not Be Taken With CBD

The use of cannabidiol has been steadily increasing and is being advertised for an ever-increasing number of conditions. However, this supplement can produce significant adverse effects when used with other medications. This article discusses these interactions.

What is CBD?

Cannabidiol (CBD) is a phytocannabinoid that can be isolated from the cannabis plant. In its pure form, CBD does not produce any psychotropic effects and has been linked to many different health benefits. Due to these benefits without the mind-altering effects, CBD has become widely popular.

Cannabidiol is available in three forms that vary in the presence of different cannabinoids, including tetrahydrocannabinol (THC). Many people that use CBD view it as a safe, natural product. However, it has been found to interact with numerous medications and should be discussed with a doctor or pharmacist before taking it.

Does CBD interfere with other drugs?

Yes, CBD can cause adverse reactions when taken with various medications. One reason for unwanted drug interactions is that CBD is metabolized in the liver by enzymes (CYP 3A4 and CYP2C19) responsible for the breakdown of many other medications. Therefore, when taken with other medications, CBD can increase the levels of these medications in the blood and result in adverse effects.

Another possible interaction between CBD and various medications is that CBD affects various receptors in the body to produce its effects. These are the same targets of many different medications and, thus, could result in various interactions. Although many of these interactions have not been thoroughly studied, it is important to discuss CBD use with a doctor or pharmacist to make sure the benefits outweigh the possible risks.

Drugs that interact with CBD

The majority of interactions involving CBD and prescription medications involve interference with the metabolism of either CBD or the medication. Thus, we will discuss the major classes of medications known to interact with CBD. However, this is not a complete list of all CBD interactions.

Anti-epileptic drugs

Many commonly prescribed anti-epileptic (anticonvulsant) drugs affect the liver enzymes responsible for metabolizing CBD. In addition, medications such as phenytoin, carbamazepine, oxcarbazepine, and phenobarbital enhance the breakdown of CBD, making it less effective. Therefore, users will not get the desired effect from the typical dosages of CBD.

Other anti-epileptic medications, such as lamotrigine, can be increased when taken with CBD, resulting in increased side effects. Additionally, ethosuximide can have its anticonvulsant effects reduced when administered with CBD, which could result in increased seizures.


Cannabidiol interacts with many benzodiazepines commonly used for seizure disorders and the treatment of anxiety. Clonazepam and chlordiazepoxide are two benzodiazepines that can have their ability to control seizures reduced when taken with CBD. Whereas the levels of lorazepam, diazepam, and clobazam are increased when taken with CBD leading to increased adverse effects.


Two of the main classes of antidepressants, selective serotonin inhibitors (SSRIs) and tricyclic antidepressants (TCAs), have been found to interact with CBD. Sertraline, an SSRI, increased aggressive behavior and anxiety when used with CBD to treat PTSD in a mouse model. The TCA, amitriptyline, is increased when taken with CBD, increasing the side effects of amitriptyline.


Cannabidiol can have varying effects when used with different opioid medications. For example, when used with morphine, CBD can increase the effects of morphine and result in reduced safety. On the other hand, fentanyl has been shown to be safe and well-tolerated when used in conjunction with CBD.

Other drugs

Cannabidiol has also been found to interact with other medications and increase their levels, for warfarin, cyclosporine, and tacrolimus, resulting in increased side effects. In addition, due to the inhibition of the enzyme responsible for metabolizing prednisone and hydrocortisone, CBD can increase the side effects associated with long-term corticosteroid therapy.

Can CBD increase the side effects of other drugs?

Yes. As stated above, CBD can inhibit the breakdown of certain medications in the body resulting in higher levels of these drugs in the body. However, these higher concentrations are associated with a wide range of side effects depending on the medication used with CBD.

These side effects can range in severity. When used with other medications, CBD interactions can result in an increased amount of drowsiness to an increased risk of life-threatening side effects such as seizures and heart arrhythmias.

CBD and alcohol

Currently, it is unknown how the interaction between CBD and alcohol affects humans, and many studies have shown conflicting results. However, it is known that when taking CBD with alcohol, CBD can increase drowsiness resulting in an increased risk of accidents, especially when operating machinery.

Conflicting results on blood alcohol levels have been seen when CBD is given in combination with alcohol. In one study, CBD resulted in no effects on blood alcohol levels, but in another, blood alcohol levels were reduced by the administration of CBD. However, the impairment due to alcohol was unchanged despite these changes in blood alcohol levels.

To highlight the uncertainty of the use of CBD with alcohol, many researchers are currently evaluating the use of CBD in hopes it can provide some benefit to the treatment of alcohol abuse disorders. Some evidence suggests CBD can reduce cravings and help with the symptoms of alcohol withdrawal.


High doses (>600 mg) of CBD have been found to prevent THC metabolism resulting in higher levels of THC and a longer duration of its mind-altering effects. However, some have suggested that CBD can help protect against the negative effects of THC and reduce the positive feelings of the THC, which could play a role in treating cannabis use disorders. Overall, it is currently unclear, the exact effect CBD and THC have on the body when used together.

Cannabidiol should not be thought of as a benign entity but rather as a medication with the possibility of interacting with other prescription and non-prescription medications. Therefore, it is essential to discuss the use of CBD with your doctor and pharmacist to prevent these interactions.

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