There are more than 80 cannabinoids found in cannabis plants, with THC being the primary one, followed by CBD. However, in the hemp plant, which is a different strain of the species Cannabis sativa, CBD is the main active ingredient, and THC is barely present, making its use and legality more widespread. The reason that CBD is such an effective form of support for human health is due to the body’s endogenous cannabinoid system. This regulatory structure of the body has millions of cannabinoid receptors in the brain and nervous system, which react not only to plant-derived cannabinoids (such as hemp and marijuana) but also to natural cannabinoids produced within our body. When hemp oil is used and processed by the body, it is effectively boosting the function of the endocannabinoid system, helping our body regulate itself in many different ways.
Pharmacology published a study in 2016 looking at medical marijuana for migraines, specifically in relation to its effects on serotonin, with very positive results. You’ll notice that neither study looked at CBD in isolation from other cannabinoids (which is an issue with a lot of research on CBD and pain). Truthfully, the research on CBD alone just isn’t sufficient to make any pronouncements about its effects on headache pain.