Should I try CBD?

CBD oil and dropper 
Cannabidiol, or CBD, has recently become widely available without a prescription in oils, gummies, drinks and lotions, both online and in stores. It’s also available through Ohio’s Medical Marijuana Program, and it’s a prescription medication – Epidiolex.
As more people turn to this hemp-derived drug to improve sleep, reduce anxiety and ease pain, they may wonder:  Does CBD work? Is CBD safe?
CBD has only one FDA-approved medical indication: To help control a specific type of childhood seizures that occur in the rare Dravet and Lennox-Gastaut syndromes. There’s no other FDA-approved medical indication for CBD, because there’s no reliable scientific evidence supporting any other medical use of CBD.
According to the World Health Organization report 2017: “CBD is generally well tolerated with a good safety profile. Reported adverse effects may be as a result of drug-drug interactions between CBD and patients’ existing medications. To date, there is no evidence of recreational use of CBD or any public health related problems associated with the use of pure CBD.”
Although CBD hasn’t been associated with problems at the public health level, the few controlled clinical trials that have been performed revealed some specific adverse effects with CBD use at the individual level.
Why do people use CBD?
CBD is commonly used to treat insomnia, anxiety and pain. CBD can be sedating, and some people find that CBD helps them both with falling asleep and with staying asleep. Possibly also related to its sedating effect, some people find that CBD reduces their anxiety. Finally, CBD receptors are found on immune system and nervous system cells throughout our bodies, and some people find that CBD reduces their pain, most commonly chronic arthritis-related pain or neuropathic pain.
However, whether CBD provides benefit beyond placebo is unknown, because there are no controlled clinical trials of CBD for treating insomnia, anxiety or pain. The placebo effect occurs when a person believes that a treatment will work, and that person’s belief in the treatment actually helps it to work.
The biological mechanisms of the placebo effect have been studied. For example, our bodies can release our own internal pain “medication”— neurotransmitters that bind to the same receptors in the nervous system that bind to morphine, thereby suppressing pain signals.
How might CBD work?
Because CBD receptors are found on cells in the immune system and the nervous system, it’s thought that the effects of CBD are caused by altering the activity of immune system and nervous system cells. For example, CBD changes serotonin release and reuptake in nerve cells around the stomach, possibly explaining why CBD can cause nausea. Analogous effects in the brain might explain CBD-related sedation.
How rapidly CBD has an effect depends on how it’s taken. Inhalation is fastest, and absorption through the mucous membranes of the mouth is next fastest. Eating/swallowing is not only the slowest, but more of the CBD is metabolized by the liver, thereby reducing the amount of CBD that gets to the rest of the body. Skin absorption of CBD is variable and depends on the concentration of CBD, the type of carrier (for example, oil, lotion, cream or tincture), and on the thickness and condition of the skin (for example, dry/moist, warm/cold or perspiring).
CBD takes two to six hours to distribute throughout the body, and is metabolized by the liver. Therefore, in a person with diminished liver function, the effects of a given dose of CBD are likely to be greater and to last longer.
Can CBD have adverse effects?
Common adverse effects of CBD include sedation, fatigue, dizziness, nausea, irritability, dry mouth and an increase in the liver enzymes to abnormal levels.
Because it’s metabolized in the liver, CBD can boost the effects of medications that are also metabolized in the liver. For example, CBD increases the effect of warfarin (Coumadin), cilostazol (Pletal) and citalopram (Celexa). Therefore, if you take medications, you should talk with your doctor about possible effects of CBD on your medications before taking CBD.
Unless purchased as prescription Epidiolex or as an herbal through Ohio’s Medical Marijuana program, CBD supplements aren’t regulated for purity and content. Testing of popular commercially available CBD products found that only 15% contained what was on their labels, and 40% contained less than one-fifth of the amount of CBD claimed on their labels, with a quarter of those (10% of the total) having no detectable CBD at all.  Also, some of the products contained high levels of solvents and dangerous gasses.
In 2019, an 8-year-old boy with a seizure disorder had a dramatic increase in seizures (14 in 24 hours) after taking a CBD oil product that contained a synthetic cannabinoid known to cause seizures.
Therefore, when you take commercially available CBD it can be difficult to know if you’re unintentionally taking other drugs, and to know how much CBD you’re actually taking, if any.
Some experts recommend making sure CBD products are: 
  • certified as organic by the U.S. Department of Agriculture
  • labeled as having been tested for pesticides and herbicides
  • labeled as meeting Current Good Manufacturing Practices by the FDA
In addition, some experts recommend using European CBD products, because Europe has a more established regulatory system for these products and European CBD products have a lower allowed concentration for tetrahydrocannabinol (THC, the psychoactive component of marijuana)— 0.2% in Europe vs 0.3% in the United States.
What medical research has been done on CBD?
In a mouse study of inflammatory arthritis, CBD reduced inflammatory markers. In a rat study of chemically-induced joint damage, CBD reduced measures of joint inflammation, measures of nerve damage and reduced pain behaviors. In another rat study, CBD reduced anxiety behaviors.
Nonetheless, at this time, other than clinical trials of Epidiolex in two rare childhood seizure syndromes, there’s been no significant CBD clinical research in people. The few clinical trials that have been done were seriously flawed by the small numbers of people studied, the lack of adequate scientific controls and the absence of long-term follow-up.
At this time, both the short- and long-term effects of CBD are unknown. In the future there might be specific synthetic medications similar to CBD that could help treat specific clinical conditions but, for now, there’s no reliable clinical evidence that CBD is effective or safe for people.
Harrison Weed is an internal medicine physician and chair of the Pharmacy and Therapeutics Committee at The Ohio State University Wexner Medical Center.

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