This is where discussions can get even more confusing. The hemp plant has naturally occurring (yet trace amounts) of tetrahydrocannabinol. If a product has THC levels above 0.3 percent (by dry weight), the government considers it marijuana. If a hemp-derived CBD product contains THC, it must be under 0.3 percent to be legal. (For perspective, the average marijuana strain today contains about 12 percent THC.)
The weather is a huge challenge for hemp growers focused on CBD products. When cannabis plants are stressed by cold weather, they can create more THC. Drought, flooding, heat or cold can all result in unintentional spikes in THC.
On the flip side, marijuana-derived CBD is illegal at the federal level and classified as a controlled substance regardless of its percentage of THC.
Even in states where marijuana is legal, there are restrictions on where CBD products are sold and how they can be marketed. A statement by the U.S. Food and Drug Administration (FDA) made clear that products that contain CBD—even if derived from legal, commercial hemp—cannot claim to have therapeutic benefits or be sold as dietary supplements unless they have been approved by the FDA for that use. This is to protect consumers by discouraging the illegal marketing of unsubstantiated health/medical claims. As of this writing, the FDA has approved only one CBD product, Epidiolex, for the treatment of rare, severe forms of epilepsy. If you are buying other CBD products today, their therapeutic benefits are unsubstantiated, and they are largely unregulated in terms of safety. (From Hazelton Betty Ford)