CBD Oil and Drug Interactions

By Aimee McNew
Myriam Zilles, Unsplash

Cannabidiol, or CBD oil as it’s often called, is an extremely promising hemp-derived supplement that is being widely researched for benefits ranging from epilepsy, anxiety, and depression, to women’s health issues like PMS, and various forms of pain management.

CBD oil seems wonderful and endlessly promising, however, it’s not for everyone. Because of the way that even the best CBD oil can interact with the nervous system and immune system, it can cause side effects. It can also interact with other medications that rely on those pathways or interact with them.

How CBD Oil is Metabolized

Cannabidiol is metabolized in the body by certain enzymes that many other drugs also rely on for delivery. This enzyme system is regulated by a set of genes known as the cytochrome p450 genes, which help to form and break down chemicals and molecules in cells, including medications, steroids, hormones, and certain fats.

The p450 enzymes are mostly located in liver cells, but are also scattered throughout the body to facilitate processing and transport. People can have normal p450 genes or mutated ones, meaning that in some, medications can metabolize faster or slower than they should. The same can be true for CBD oil. The cytochrome p450 enzyme system is responsible for nearly 80 percent of all drug metabolism, which also includes supplements and other medicinal substances.

The specific cytochrome p450 enzymes that are involved in CBD oil metabolism are CYP3A4 and CYP2C19. When other medications rely on these enzymes, CBD oil can interrupt the process and compete with receptors for these genetic enzymes, resulting in altered absorption rates and changing blood levels of the drugs, potentially requiring adjusted doses for the same effect.

CBD Oil and Medication Interactions

People take CBD oil for many reasons, some backed by research and others not, including epilepsy, muscle disorders, insomnia, multiple sclerosis, and more. In many cases, they might be taking prescription medications for these same conditions or for other health problems. Because CBD oil is often found in supplement form, it may not always be prescribed or recommended by a doctor, and an alarming number of patients (more than half) don’t run their supplements by their doctors to check for interactions.

Cannabidiol has some side effects, but on its own, they’re not severe, typically ranging from mild nausea to fatigue. CBD oil is considered “possibly safe” when taken by mouth in doses of up to 300 milligrams daily, however, several categories of people are excluded, including pregnant women, breastfeeding women, and children unless explicitly prescribed by their doctor. People with Parkinson’s should also avoid CBD oil because higher doses can increase tremors and worsen muscle control.

Otherwise, people taking certain medications need to be extremely cautious of CBD oil. There are several types of drugs that have major interactions with cannabidiol and should not be used together, including:

1. Anti-Seizure Medications

The strongest interactions occur with two medications that are used to treat seizures and epilepsy, Clobazam and Valproic acid. These should never be taken with CBD oil as there is a strong potential for serious liver damage.

Other anticonvulsant medications, also used to treat seizures, could have interactions with cannabidiol and should be avoided. This especially includes Eslicarbazepine.

2. Muscle Relaxers

Certain types of medications are broken down by the liver and utilize the same cytochrome p450 pathways that CBD oil does. This means that cannabidiol can increase the effects of these medications or decrease them, but either way, it will interfere with the proper action of the prescription. Muscle relaxers like chlorzoxazone are often used to treat pain or muscle spasms. People suffering from these symptoms might find CBD oil appealing and need to be cautious not to take them concurrently. Orphenadrine is another muscle relaxant often used for injury relief that also interacts with CBD oil.

3. Asthma Medication and Bronchodilators

Some medications that relieve the symptoms of asthma also rely on the same p450 pathways that CBD oil does, including theophylline. If you take medications for asthma, you should check with your doctor before adding CBD oil.

4. Antidepressants and Antipsychotics

Medications that treat depression and other types of nerve pain, such as amitriptyline, require the liver to change and break them down, much like CBD oil. Antipsychotics like haloperidol act on the same pathway and should not be paired with cannabidiol.

5. Beta Blockers

Propranolol and verapamil, beta blockers that are used to treat blood pressure, atrial fibrillation, and angina, utilize the p450 pathway to be metabolized and used. Cannabidiol can change the way that these prescriptions work, and should not be used in conjunction with CBD oil unless expressly approved by a doctor.

6. Proton Pump Inhibitors

Used to treat heartburn, acid reflux, and GERD, proton pump inhibitors (PPIs) interact with CBD oil because of their reliance on the liver and the cytochrome p450 pathway. These include lansoprazole, omeprazole, and others.

7. Hormones

Progesterone is a hormone that is part of the female reproductive system. It is often prescribed for birth control, fertility treatments, pregnancy, preventing pre-term labor, and addressing certain aspects of menopause. Progesterone interacts with CBD oil, like many other drugs, because hormone medications must be broken down by the liver to be used in the body.

8. Chemotherapy Drugs

Certain types of chemotherapy medications are hormone-based and rely on the liver to metabolize them, including flutamide, which is used for prostate cancer, or oxaliplatin, which is used for colon cancer. It also includes other types of chemotherapy used for lung cancer and pancreatic cancer.

9. Blood Thinners

Warfarin, a blood thinner that is often used to treat people who have had blood clots, can have serious side effects and requires specific dosing to ensure effective protection without too much or too little clotting capabilities. CBD oil interferes with the ability of this drug to be regulated and should not be taken at the same time.

10. Pain Medications

Various types of pain medications, ranging from methoxyflurane (which is used for post-traumatic pain) to NSAIDs like ibuprofen, rely on the liver to metabolize and activate them. CBD oil also has pain-relieving qualities that are activated by the same pathway. Taking these drugs together with CBD oil is not recommended because they can interfere with the proper metabolism.

11. Anti-Anxiety Drugs and Sedatives

People who deal with anxiety or have insomnia or other sleep issues often rely on medication to provide relief, including popular prescriptions like Valium. These, however, interact with CBD oil and should not be used together.

CBD Oil and Supplements

Cannabidiol can interact with other herbal supplements, too, especially those that boast similar benefits to CBD oil: relaxants, sleep aids, antidepressants, mood boosters, and any that address inflammation or pain. These could include St. John’s wort, hops, catnip, kava, tryptophan, sage, valerian root, and more.


Bottom Line

This is not an exhaustive list of all medications that interact with CBD oil. If you take any type of prescription medication or supplement, you should consult your practitioner before deciding whether or not CBD is safe for you. There are many promising benefits of CBD oil, and in many cases, fewer side effects than numerous prescription drugs. But replacing your medications with CBD oil should never be done unless at the suggestion of your prescribing practitioner.

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