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Cannabidiol (CBD) is an active ingredient found in marijuana, but it does not cause the same mind-altering “high” that tetrahydrocannabinol (THC) does. Research shows that CBD can have several benefits for various ailments, such as pain, inflammation, and anxiety. Epidiolex, an FDA-approved CBD medication, is used to treat certain types of seizures.
As the potential uses of CBD continue to expand, more people are finding an interest in over-the-counter CBD products. In fact, CBD product sales in the United States are projected to hit almost $16 billion in 2026. While browsing your local pharmacy, health spa, gas station, or coffee shop, you might come across different CBD products. These products might come in the form of oral capsules, supplements, topical creams, and oils or extracts containing varying amounts of CBD.
Although CBD is legal on a federal level, it is not free of safety risks. With the increasing popularity of over-the-counter CBD products, it’s important to be aware of the possible side effects and drug interactions that can arise. CBD drug interactions can be a serious concern, especially for people who take commonly prescribed medications like antidepressants and blood thinners. CBD drug interactions can lead to increased side effects or other problems if left unchecked.
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What you need to know about CBD drug interactions
CBD produces a calming effect and relieves symptoms of various conditions by interacting with serotonin and cannabinoid receptors throughout the body. It is an effective medicine that is considered well-tolerated with mild side effects. However, serious side effects and drug interactions are possible with CBD. Before using CBD, it’s important to consult a healthcare provider for medical advice, especially if you take medications for other health conditions.
CBD and the CYP450 liver enzymes
CBD is extensively processed or metabolized in the liver by the cytochrome P450 (CYP) enzyme system. How these liver enzymes metabolize CBD plays a large role in CBD’s potential drug interactions. That’s because numerous drugs, including certain antifungals, seizure medications, and antibiotics, can alter the activity of CYP enzymes.
Drugs that block CYP enzymes, called enzyme inhibitors, can decrease the metabolism of CBD, which can lead to increased blood levels and side effects of CBD. Drugs that increase CYP enzyme activity, called enzyme inducers, can speed up the metabolism of CBD and decrease its overall effectiveness.
One aspect of CBD makes it particularly susceptible to drug interactions. Not only is CBD processed by the CYP enzymes, but it can also act as a CYP enzyme inhibitor. Specifically, CBD can block the enzymes that process other drugs, such as certain seizure medications, antidepressants, and pain relievers. In simple terms, taking CBD can lead to increased blood levels and side effects of other medications.
Overlapping side effects of CBD and other drugs
CBD can cause side effects that overlap with those of other drugs. CBD’s most common side effects include drowsiness, fatigue, diarrhea, decreased appetite, and sleep disturbances. CBD can also cause serious side effects, such as liver damage and suicidal thoughts or behaviors. As some medications can cause similar side effects, it’s important to use CBD with caution while taking other medications.
What drugs should not be taken with CBD?
Almost 60% of prescription medications are processed through the same group of enzymes as CBD, which can lead to several drug interactions. In addition, there are various drugs that cause the same side effects as CBD. It’s a good idea to keep a list of current medications and work with a healthcare provider to ensure CBD is taken safely.
The use of the following medication classes could lead to potential CBD drug interactions.
Antiepileptic drugs
CBD is commonly used along with anticonvulsants or antiepileptic drugs, but it is known to interact with several antiepileptic drugs. Certain antiepileptic drugs, including carbamazepine, oxcarbazepine, phenobarbital, and phenytoin, can affect the metabolism of CBD and lead to decreased levels of CBD. Combining CBD with these antiepileptic drugs can ultimately lead to decreased effects of CBD.
Studies have shown that taking CBD with Depakote (valproic acid or valproate) can lead to abnormally high liver enzyme levels, which could indicate liver problems. Patients who are using CBD with these antiepileptic drugs should be monitored for liver disease or injury.
In addition, CBD may increase the effects of some antiepileptic drugs, such as phenobarbital and phenytoin, which could lead to toxicity from these antiepileptic drugs. Dosage adjustments and increased monitoring may be needed for people who mix antiepileptic drugs and CBD.
Antidepressants
CBD can block the actions of the CYP2D6 enzyme, which can result in the decreased metabolism and increased blood levels of certain antidepressants, including tricyclic antidepressants (TCAs) and selective serotonin reuptake inhibitors (SSRIs). This interaction can then lead to increased side effects of antidepressants.
The side effects of CBD and antidepressants can also overlap, as CBD and antidepressants are associated with central nervous system (CNS) side effects, such as drowsiness and sleep disturbances. In addition, CBD and antidepressants can cause an increased risk of suicidal thoughts or behaviors.
Benzodiazepines
CBD can alter the metabolism of benzodiazepines, which are prescription drugs that can treat insomnia, anxiety, or seizures. In particular, the use of CBD can increase blood levels of several benzodiazepines, including clobazam, diazepam, and lorazepam, which can lead to increased side effects of these benzodiazepines.
Certain side effects of CBD and benzodiazepines can overlap. There may also be an increased risk of drowsiness and problems with coordination when using CBD with benzodiazepines. Healthcare providers will want to closely monitor the use of benzodiazepines with CBD to prevent severe side effects.
Opioid analgesics
Potential interactions exist between CBD and opioid pain relievers. For instance, CBD can decrease the metabolism of morphine, which may lead to increased blood levels and side effects of morphine. CBD and opioids also share similar CNS side effects, including drowsiness, sedation, fatigue, and lethargy. People with severe chronic pain should weigh the benefits and risks of mixing CBD and opioids.
Blood thinners
The use of CBD can also alter the metabolism of different blood thinners, including anticoagulants and antiplatelet agents. Taking CBD with warfarin may lead to an increased risk of bleeding. One case report found that a patient taking CBD and warfarin needed to reduce their warfarin dose by 30% to decrease the risk of bleeding. Clopidogrel is an antiplatelet agent that is metabolized into an active form in the liver. CBD can block the metabolism of clopidogrel, making the medication less effective and increasing the risk of stroke.
Immunosuppressants
CBD can increase the blood levels of immunosuppressants like tacrolimus and cyclosporine, leading to toxic levels of immunosuppressants and increased side effects. Taking CBD has been shown to increase the risk of viral infections and pneumonia in some people due to its effects on the immune system. Combining CBD with an immunosuppressant may increase the risk of severe infections.
Proton pump inhibitors
Proton pump inhibitors (PPIs), such as omeprazole, pantoprazole, and lansoprazole, are processed by the CYP enzymes. As CBD use can interfere with the function of the CYP enzymes, mixing CBD and PPIs could lead to increased side effects of PPIs. CBD and PPIs can also have overlapping side effects, such as diarrhea.
Certain antimicrobials
Certain antibiotics, such as clarithromycin and erythromycin, as well as antifungals, such as ketoconazole and itraconazole, can block the liver enzymes that process CBD. Taking CBD with certain antimicrobials can lead to increased blood levels of CBD, which can lead to negative side effects of CBD.
Blood pressure medications
Researchers have found that CBD can lower blood pressure, which can be a concern in people who are taking high blood pressure medications. Taking CBD with blood pressure medications could lead to low blood pressure, fainting, and falls. People who take high blood pressure medications, such as ACE inhibitors, beta blockers, or diuretics, may need to monitor blood pressure while using CBD.
Herbal and dietary supplements
Some herbal and dietary supplements, such as St. John’s wort, can alter the metabolism of CBD. Taking St. John’s wort with CBD can lead to decreased blood levels and reduced effects of CBD. Research has shown that ginkgo biloba also has the potential to alter the metabolism of CBD as a liver enzyme inhibitor, although the effect may not be significant.
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CBD and alcohol
Mixing CBD and alcohol should be avoided. CBD and alcohol share CNS side effects, such as drowsiness and sedation. Taking CBD and alcohol together could increase the risk of experiencing these CNS side effects. CBD and alcohol have also been reported to affect the liver. Combining CBD and alcohol could increase the risk of liver damage.
CBD can interact with other types of drugs not listed here, including statins, diabetes medications, and chemotherapy drugs. It can also interact with certain foods and beverages, such as fatty foods and grapefruit juice. Make sure to tell a healthcare provider about any medications you take, including prescription drugs, over-the-counter medicine, and herbal supplements, before starting treatment with CBD.
Who is most at risk for CBD interactions?
Some people may be at a higher risk of drug-drug interactions involving CBD than others. Special precautions should be taken for people who are more likely to experience an interaction while taking CBD.
Older adults
Older adults are more likely to experience drug-drug interactions than younger adults because they have a greater risk of kidney or liver problems. As we age, our organs start to change and decline, altering how drugs are processed in the body. As CBD is processed in the liver, along with many other medications, older adults may be at an increased risk of high drug levels in the body and adverse effects.
People taking multiple medications
People who take several medications are at a greater risk of drug interactions. Different medications can influence or alter how other medications are processed. Side effects of medications can also overlap, which can lead to serious complications. It’s important to use caution before mixing CBD and multiple medications, especially if you have multiple health conditions.
The bottom line: Balancing risks and benefits of CBD
CBD is generally well-tolerated when used with the guidance of a doctor, pharmacist, or other healthcare provider. It is available in different dosage forms and can offer benefits for patients who experience various ailments. However, Epidiolex is the only FDA-approved CBD oil, which is available to treat certain types of seizures.
Potential problems with CBD can arise with over-the-counter or unregulated CBD products. For example, many CBD products are not tested for purity and may contain higher or lower concentrations than what is labeled.
Hemp-derived CBD is legal in all states. But before purchasing marijuana-derived CBD, it’s important to check state laws, as certain states have their own rules and regulations. While CBD can be useful for some patients, further research is needed to evaluate the safety and effectiveness of CBD. A healthcare provider can help weigh the therapeutic effects against potential CBD interactions and side effects. In addition, a healthcare provider can help recommend an appropriate dose of CBD, based on the condition being treated.
