The tricky part is that there's some evidence suggesting CBD works best for pain when combined with a little THC, says Dr. Danesh. "Depending on what type of pain you have, you might be able to do just CBD, but sometimes you need CBD and THC." This makes accessing a product that will actually help you more difficult due to different regulations in each state. In New York, where Dr. Danesh practices, for example, CBD is available over the counter. But as soon as you add THC, you need a prescription.
Until 2017, products containing cannabidiol marketed for medical purposes were classed as medicines by the UK regulatory body, the Medicines and Healthcare products Regulatory Agency (MHRA) and could not be marketed without regulatory approval for the medical claims. As of 2018, cannabis oil is legal to possess, buy, and sell in the UK, providing the product does not contain more than 0.2% THC and is not advertised as providing a medicinal benefit.
^ Klein C, Karanges E, Spiro A, Wong A, Spencer J, Huynh T, Gunasekaran N, Karl T, Long LE, Huang XF, Liu K, Arnold JC, McGregor IS (November 2011). "Cannabidiol potentiates Δ⁹-tetrahydrocannabinol (THC) behavioural effects and alters THC pharmacokinetics during acute and chronic treatment in adolescent rats". Psychopharmacology. 218 (2): 443–457. doi:10.1007/s00213-011-2342-0. PMID 21667074.
Laboratory evidence indicated that cannabidiol may reduce THC clearance, increasing plasma concentrations which may raise THC availability to receptors and enhance its effect in a dose-dependent manner. In vitro, cannabidiol inhibited receptors affecting the activity of voltage-dependent sodium and potassium channels, which may affect neural activity. A small clinical trial reported that CBD partially inhibited the CYP2C-catalyzed hydroxylation of THC to 11-OH-THC.