In addition, the stroke volume (the amount of blood remaining in the heart after a heartbeat) was significantly reduced, meaning that the heart was pumping more efficiently.
In an analysis of 14 published studies (nine involving animals and five involving humans), scientists with the University of Montreal concluded that CBD showed promise in treating people with opioid, cocaine, or psychostimulant addiction.
CBD shows promise in the treatment of anxiety disorders, suggests a 2015 review of studies in the journal Neurotherapeutics. According to the investigators, CBD demonstrated potent anxiolytic (anxiety-relieving) effects in animal research, albeit with counterintuitive results.
There is some evidence that CBD interacts with seizure medications such as Onfi (clobazam) and boosts their concentration in the blood. Further research is needed.
Remember, because CBD oils are largely unregulated, there is no guarantee that a product is either safe or effective.
CBD oil may reduce the risk of heart disease by alleviating hypertension (high blood pressure) in certain people, suggests a 2017 study in JCI Insight.
Medical marijuana is frequently prescribed to people with intractable (treatment-resistant) pain, including those with terminal cancer. There is some evidence that CBD contributes to this benefit.
McAllister SD, Murase R, Christian RT, et al. Pathways mediating the effects of cannabidiol on the reduction of breast cancer cell proliferation, invasion, and metastasis. Breast Cancer Res Treat 2011;129(1):37-47. View abstract.
Brady CM, DasGupta R, Dalton C, et al. An open-label study of cannabis-based extracts for bladder dysfuntion in advanced multiple sclerosis. Mult Scler 2004;10(4):425-33. View abstract.
Klotz KA, Hirsch M, Heers M, Schulze-Bonhage A, Jacobs J. Effects of cannabidiol on brivaracetam plasma levels. Epilepsia. 2019;60(7):e74-e77. View abstract.
Special Precautions and Warnings
Taylor L, Crockett J, Tayo B, Checketts D, Sommerville K. Abrupt withdrawal of cannabidiol (CBD): A randomized trial. Epilepsy Behav. 2020;104(Pt A):106938. View abstract.
Leino AD, Emoto C, Fukuda T, Privitera M, Vinks AA, Alloway RR. Evidence of a clinically significant drug-drug interaction between cannabidiol and tacrolimus. Am J Transplant. 2019;19(10):2944-2948. View abstract.
Zuardi AW, Morais SL, Guimaraes FS, Mechoulam R. Antipsychotic effect of cannabidiol. J Clin Psychiatry 1995;56(10):485-6. View abstract.
Bloomfield MAP, Green SF, Hindocha C, et al. The effects of acute cannabidiol on cerebral blood flow and its relationship to memory: An arterial spin labelling magnetic resonance imaging study. J Psychopharmacol. 2020;34(9):981-989. View abstract.
CBD has the potential to interact with many other products, including over-the-counter medications, herbal products, and prescription medications. Some medications should never be taken with CBD; the use of other medications may need to be modified or reduced to prevent serious issues. The consequences of drug interactions also depend on many other factors, including the dose of CBD, the dose of another medication, and a person’s underlying health condition. Older adults are more susceptible to drug interactions because they often take multiple medications, and because of age-related physiological changes that affect how our bodies process medications.
Researchers from Penn State College of Medicine evaluated existing information on five prescription CBD and delta-9-tetrahydrocannabinol (THC) cannabinoid medications: antinausea medications used during cancer treatment (Marinol, Syndros, Cesamet); a medication used primarily for muscle spasms in multiple sclerosis (Sativex, which is not currently available in the US, but available in other countries); and an antiseizure medication (Epidiolex). Overall, the researchers identified 139 medications that may be affected by cannabinoids. This list was further narrowed to 57 medications, for which altered concentration can be dangerous. The list contains a variety of drugs from heart medications to antibiotics, although not all the drugs on the list may be affected by CBD-only products (some are only affected by THC). Potentially serious drug interactions with CBD included
Absolutely. Inhaled CBD gets into the blood the fastest, reaching high concentration within 30 minutes and increasing the risk of acute side effects. Edibles require longer time to absorb and are less likely to produce a high concentration peak, although they may eventually reach high enough levels to cause an issue or interact with other medications. Topical formulations, such as creams and lotions, may not absorb and get into the blood in sufficient amount to interact with other medications, although there is very little information on how much of CBD gets into the blood eventually. All of this is further complicated by the fact that none of these products are regulated or checked for purity, concentration, or safety.
The bottom line: Talk to your doctor or pharmacist if using or considering CBD
People considering or taking CBD products should always mention their use to their doctor, particularly if they are taking other medications or have underlying medical conditions, such as liver disease, kidney disease, epilepsy, heart issues, a weakened immune system, or are on medications that can weaken the immune system (such as cancer medications). A pharmacist is a great resource to help you learn about a potential interaction with a supplement, an herbal product (many of which have their own drug interactions), or an over-the-counter or prescription medication. Don’t assume that just because something is natural, it is safe and trying it won’t hurt. It very well might.
Many drugs are broken down by enzymes in the liver, and CBD may compete for or interfere with these enzymes, leading to too much or not enough of the drug in the body, called altered concentration. The altered concentration, in turn, may lead to the medication not working, or an increased risk of side effects. Such drug interactions are usually hard to predict but can cause unpleasant and sometimes serious problems.
Products containing cannabidiol (CBD) seem to be all the rage these days, promising relief from a wide range of maladies, from insomnia and hot flashes to chronic pain and seizures. Some of these claims have merit to them, while some of them are just hype. But it won’t hurt to try, right? Well, not so fast. CBD is a biologically active compound, and as such, it may also have unintended consequences. These include known side effects of CBD, but also unintended interactions with supplements, herbal products, and over-the-counter (OTC) and prescription medications.
While generally considered safe, CBD may cause drowsiness, lightheadedness, nausea, diarrhea, dry mouth, and, in rare instances, damage to the liver. Taking CBD with other medications that have similar side effects may increase the risk of unwanted symptoms or toxicity. In other words, taking CBD at the same time with OTC or prescription medications and substances that cause sleepiness, such as opioids, benzodiazepines (such as Xanax or Ativan), antipsychotics, antidepressants, antihistamines (such as Benadryl), or alcohol may lead to increased sleepiness, fatigue, and possibly accidental falls and accidents when driving. Increased sedation and tiredness may also happen when using certain herbal supplements, such as kava, melatonin, and St. John’s wort. Taking CBD with stimulants (such as Adderall) may lead to decreased appetite, while taking it with the diabetes drug metformin or certain heartburn drugs (such as Prilosec) may increase the risk of diarrhea.