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.
More human studies are needed to fully understand the range of risks and side effects that CBD oil may cause. Studies of CBD oil aren’t common. This is partially because Schedule 1 substances like cannabis are highly regulated, causing some obstacles for researchers. With the legalization of marijuana products, more research is possible, and more answers will come.
Research on CBD and anxiety has generally looked at cannabis as a whole product, not as CBD as a standalone compound. Some studies suggest that it can help with anxiety: like this 2011 study that suggests CBDcan reduce social anxiety or this 2015 review that says CBD could be promising for many forms of anxiety. It’s also important to consider whether the CBD comes from the cannabis plant and therefore may include THC, a cannabinoid that for some, induces anxiety. Read our comprehensive article on CBD and anxiety, here.
But scientists have found that CBD doesn’t bind well with endocannabinoid receptors. Instead, CBD influences the system indirectly. This creates many benefits, which is why you’ll hear of CBD as a treatment for so many different medical conditions. And, unlike THC, it won’t make you high. When it comes to pain, we know that CBD has multiple functions. First, it influences neurotransmitters and receptors. One receptor known to be involved with pain and inflammation is called TRPV1 — also known as a vanilloid receptor. CBD binds to the TRPV1 receptor, influencing the way you perceive pain. CBD can also affect the production of neurotransmitters like serotonin and glutamate, which are related to pain sensation.

A major theme when reviewing the research on the best CBD for pain is the need for more large-scale clinical trials on CBD in isolation from other cannabinoids like THC. That’s not to say that THC is bad. It’s developed a stigma because it makes you high, which makes people think of hippies and the sixties and maybe your perennially stoned neighbor who clearly doesn’t have his stuff together. But THC also comes with a pretty respectable list of benefits. These range from antiemetic (anti-nausea) and anti-inflammatory effects to appetite stimulation.
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.
Dry Mouth: As is the case with many other hemp- and marijuana-based products, CBD oil often leads to a condition known as dry mouth (or cottonmouth). This is likely due to cannabinoids altering receptors in the lower jaw that trigger salivation. In most cases, mild discomfort and stronger-than-average thirst are the only issues associated with dry mouth.
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