Cannabidiol did not reduce responses to negative emotional stimuli or reduce anxiety in healthy participants, according to a study published in Cannabis and Cannabinoid Research in 2017. Researchers tested participants' responses to negative images or words and threatening emotional faces and sensitivity to social rejection after taking oral cannabidiol.
Under federal law, cannabis (from which both CBD and marijuana are derived) is illegal everywhere, although the laws against it aren’t generally enforced in states that have legalized marijuana. Some manufacturers claim that CBD culled from legally imported industrial hemp, which has little to no THC, is fine to ship across the U.S., but many experts disagree, noting that because hemp comes from the same species as marijuana, cannabis sativa, all CBD falls under the DEA’s Schedule 1 designation. “This creative interpretation of the law runs afoul of reality,” says the Brookings Institution, a Washington, DC, think tank.
Multiple sclerosis (MS). A prescription-only nasal spray product (Sativex, GW Pharmaceuticals) containing both 9-delta-tetrahydrocannabinol (THC) and cannabidiol has been shown to be effective for improving pain, muscle-tightness, and urination frequency in people with MS. This product is used in over 25 countries outside of the United States. But there is inconsistent evidence on the effectiveness of cannabidiol for symptoms of multiple sclerosis when it is used alone. Some early research suggests that using a cannabidiol spray under the tongue might improve pain and muscle tightness, but not muscle spasms, tiredness, bladder control, mobility, or well-being and quality of life in patients with MS.
^ Hayakawa K, Mishima K, Hazekawa M, Sano K, Irie K, Orito K, Egawa T, Kitamura Y, Uchida N, Nishimura R, Egashira N, Iwasaki K, Fujiwara M (January 2008). "Cannabidiol potentiates pharmacological effects of Delta(9)-tetrahydrocannabinol via CB(1) receptor-dependent mechanism". Brain Research. 1188: 157–64. doi:10.1016/j.brainres.2007.09.090. PMID 18021759.
Lisa Hamilton, a jeweler and doula in Brooklyn, NY, knows about the side effects. She recently tried CBD for the shoulder pain that plagued her five years after an accident. Her doctor certified that she was in chronic pain, which under New York State law allowed her to buy from a state dispensary. One Friday, she swallowed two 10-mg capsules, the amount recommended at the dispensary, then took another two on Saturday. “By Sunday, it felt like I’d gotten hit by a truck. Every muscle and joint ached,” Hamilton says. She cut back to one pill a day the following week, but still felt hungover. She stopped after that.
Marijuana can produce acute psychotic episodes at high doses, and several studies have linked marijuana use to increased risk for chronic psychosis in individuals with specific genetic risk factors. Research suggests that these effects are mediated by THC, and it has been suggested that CBD may mitigate these effects.xxxi There have been a few small-scale clinical trials in which patients with psychotic symptoms were treated with CBD, including case reports of patients with schizophrenia that reported conflicting results; a small case study in patients with Parkinson’s disease with psychosis, which reported positive results; and one small randomized clinical trial reporting clinical improvement in patients with schizophrenia treated with CBD.xxxii Large randomized clinical trials would be needed to fully evaluate the therapeutic potential of CBD for patients with schizophrenia and other forms of psychosis.