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DEAR MAYO CLINIC: I'm interested in trying CBD for knee pain. I see CBD for sale everywhere — even at gas stations. How do I figure out which kind to buy? Are CBD products that are available without a prescription safe and effective?
ANSWER: When it comes to trying products made with cannabidiol, or CBD, that you can buy without a prescription, be careful. There's some preliminary research that shows potential benefits of using CBD for certain medical problems, particularly pain, sleep disorders and anxiety. But at this time, there's no consistent oversight to ensure the purity and safety of nonprescription CBD products, or to verify claims manufacturers make about them. Before you try CBD, talk to your health care provider.
CBD is a chemical found in marijuana, but it doesn't contain tetrahydrocannabinol, or THC, the psychoactive ingredient in marijuana that produces a high. The typical formulation of CBD is a liquid that you take orally. But CBD is sold as an extract, a vaporized liquid and an oil-based capsule, too. There also are many CBD-infused products, including food, drinks and beauty products.
The only CBD product specifically approved by the Food and Drug Administration is Epidiolex, a prescription medication that's used to treat two types of epilepsy: Lennox-Gastaut syndrome and Dravet syndrome. Aside from Epidiolex, which is approved nationwide, laws vary from state to state regarding other forms of CBD.
CBD production is not tightly regulated. That means it's difficult to know exactly what's in the CBD products for sale in your community or if the dose listed on the container matches what actually is in the product. Some CBD products include chemicals and herbs, such as echinacea, that may or may not be listed on the label. One study of 84 CBD products bought online found that more than one-quarter of the products contained less CBD than labeled. In addition, THC was found in 18 of those products.
At this time, there is no definitive evidence to support the effectiveness of nonprescription CBD to treat specific medical problems. But research is ongoing into CBD as a treatment for a wide range of conditions, including pain, sleep disorders, anxiety, Parkinson's disease, schizophrenia, diabetes and multiple sclerosis. Some evidence suggests that CBD may be useful in treating pain, indicating that there could be a role for CBD as an alternative to opioid medication for challenging chronic pain or to treat opioid addiction.
Before you try nonprescription CBD for any medical concern, you need to talk with your health care provider. There are a few reasons for that. First, CBD can interfere with other medications, so it's important to review your current medications with your health care provider to confirm that CBD won't affect them.
Second, CBD can cause side effects, including dry mouth, diarrhea, reduced appetite, drowsiness and fatigue. It also can affect liver function. Before you begin taking CBD, your health care provider may recommend a liver function test, along with follow-up tests while you're taking CBD, to check that your liver is not being damaged.
Third, if you and your health care provider decide CBD may be worthwhile for you, he or she can help you determine which product to buy. Certain brands and preparations of nonprescription CBD have been tested to verify the amount of CBD they contain and identify other ingredients in them. Your health care provider can help you find one of those verified products. Do not take a nonprescription CBD product without consulting your health care provider first. Although CBD shows some promise, many CBD products on the market today are poorly regulated, and manufacturer's claims about their benefits are unsubstantiated, so it's important to proceed with caution. — Dr. Brent Bauer, Complementary and Integrative Medicine Program, Mayo Clinic, Rochester, Minnesota