Cannabidiol (CBD) has been gaining some serious attention since the 2018 Farm Bill was signed into law, making hemp and hemp-derived products much more widely accessible in the United States. Millions of people have started to use CBD as a part of their daily health and wellness routine - whether as a natural alternative for traditional pharmaceuticals or simply as a way to boost a balanced body and mind. Unlike many medications, CBD alone is associated with very few mild side effects. But is it safe to use with other medications?
According to the World Health Organization (WHO), CBD is tolerated well among most people and is generally safe for human use. Nonetheless, it should be treated the same way as any other pharmaceutical or medication. The known side effects of cannabinoids alone are minimal and low-risk when used responsibly. Research to date indicates that CBD can effectively ease symptoms associated with a host of health conditions as well as provide general relief to the everyday user. However, those who take prescription medication or have certain medical conditions should use discretion before starting CBD. Always speak with your doctor or local pharmacist if you are planning to introduce cannabinoids to your health and wellness routine.
CYP450, Metabolism, & CBD
Your body breaks down food, medication, and other substances through a process called metabolization. Cytochrome P450 (CYP450) is a family of enzymes whose task is to metabolize foreign substances in the liver, including cannabinoids and some pharmaceuticals, before they are excreted. These enzymes play an important role in processing medications and making sure there isn’t too much or too little in your body at a time. However, the effects of cannabinoids can potentially alter the function of CYP450 liver enzymes, which may interfere with certain medications. This is why you should always consult your doctor or a pharmacist before using CBD or other cannabinoids.
Why might this happen? In part, it has to do with the Endocannabinoid System (ECS). Cannabinoids help to support and rebalance the ECS, which plays a regulatory role in a variety of bodily functions, including metabolism. When CBD interacts with the ECS, it can affect your drug metabolism rate and the way your CYP450 enzymes process medication. Your body may then begin to metabolize medications too slowly or too fast. A decrease in drug metabolism rates may lead to higher concentrations of medication building up in the bloodstream as it takes longer to process and eliminate the substance. This build up could amplify any adverse side effects associated with your prescription or even cause overdose. If the opposite occurs and drug metabolism rates increase, your medication may be less effective as there is not enough in your system at a time. Your doctor may want to alter your medication dosage should either possibility arise.
The specific enzyme responsible for breaking down CBD - and roughly 60% of pharmaceuticals - is the CYP3A4 enzyme. CBD can interfere with CYP3A4 and prevent the body from effectively metabolizing certain medications. Some medications can also inhibit CYP3A4. If you take these medications, you may not experience the full effects of CBD. Always speak with your doctor about potential interactions between CBD and your prescription medications.
You can use one simple rule to know whether CYP450 liver enzymes affect your prescription: the “grapefruit test.” Grapefruit should not be eaten when taking certain prescription medications as it can increase the level of medication in your system and cause potentially severe side effects. Look for any warning labels on your medication packaging or speak with your doctor or pharmacist to learn if you should not eat grapefruit with your medicine. If you are advised against consuming grapefruit while taking your prescription medication, you should also use caution when taking CBD.
The Indiana University School of Medicine Drug Interactions Flockhart Table provides an extensive list of drugs that use the CYP450 family of enzymes, some of which include:
Angiotensin II blockers
Antibiotics (Amoxicillin, Cephalexin, Doxycycline, etc.)
Antidepressants (Fluoxetine, Citalopram, Escitalopram, etc.)
Antiepileptics (Carbamazepine, Diazepam, Phenytoin, Clonazepam, etc.)
Antihistamines (Zyrtec, Benadryl, Clarinex, etc.)
Antipsychotics (Prolixin, Zyprexa, Abilify, etc.)
Calcium channel blockers
HMG CoA reductase inhibitors
Oral hypoglycemic agents
These are just examples - not an exhaustive list. Consult with a medical professional before beginning or altering your CBD routine if you are on prescription medications or take any kind of supplement.
CBD & Medical Conditions
Those with certain medical conditions should also use caution when using CBD - particularly those with glaucoma. Those with glaucoma or predisposed to the condition are often advised against using CBD as high doses may increase ocular pressure and elevate symptoms. THC tends to lower ocular pressure and relieve symptoms of those with glaucoma but may be prevented from doing so when CBD is also consumed.
Research to determine which other conditions may worsen with CBD use is ongoing. If you have a health condition, talk with your physician to determine whether CBD is safe for you to use.