Some manufacturers ship CBD products nationally, an illegal action which the FDA has not enforced in 2018, with CBD remaining the subject of an FDA investigational new drug evaluation, and is not considered legal as a dietary supplement or food ingredient as of December 2018.[70][71] Federal illegality has made it difficult historically to conduct research on CBD.[72] CBD is openly sold in head shops and health food stores in some states where such sales have not been explicitly legalized.[73][74]
In Western Europe, the cultivation of hemp was not legally banned by the 1930s, but the commercial cultivation stopped by then, due to decreased demand compared to increasingly popular artificial fibers.[148] Speculation about the potential for commercial cultivation of hemp in large quantities has been criticized due to successful competition from other fibers for many products. The world production of hemp fiber fell from over 300,000 metric tons 1961 to about 75,000 metric tons in the early 1990s and has after that been stable at that level.[149]

The most pressing need of the hemp industry in North America is for the breeding of more productive oilseed cultivars. At present, mainly European cultivars are available, of which very few are suitable for specialized oilseed production. More importantly, hempseed oil is not competitive, except in the novelty niche market, with the popular food oils. As argued above, to be competitive, hemp should produce approximately 2 t/ha; at present 1 t/ha is considered average to good production. Doubling the productive capacity of a conventional crop would normally be considered impossible, but it needs to be understood just how little hemp has been developed as an oilseed. There may not even be extant land races of the kind of hemp oilseed strains that were once grown in Russia, so that except for a very few very recent oilseed cultivars, there has been virtually no breeding of oilseed hemp. Contrarily, hemp has been selected for fiber to the point that some breeders consider its productivity in this respect has already been maximized. Fiber strains have been selected for low seed production, so that most hemp germplasm has certainly not been selected for oilseed characteristics. By contrast, drug varieties have been selected for very high yield of flowers, and accordingly produce very high yield of seeds. Drug varieties have been observed to produce more than a kilogram of seed per plant, so that a target yield of several tonnes per hectare is conceivable (Watson and Clarke 1997). Of course, the high THC in drug cultivars makes these a difficult source of germplasm. However, wild plants of C. sativa have naturally undergone selection for high seed productivity, and are a particularly important potential source of breeding germplasm.

The exploding recreational market for marijuana has rapidly popularized many methods of consuming cannabis that was decidedly part of the fringe just a few short years ago. Smoking marijuana remains the most widely embraced method, due to the greater accessibility of marijuana flower. But legal recreational cannabis is introducing many marijuana users to new forms of the drug, especially concentrates and edibles. Here’s a brief overview of the major methods for consuming marijuana.
Oral dronabinol (THC) is marketed in synthetic form as Marinol® (Solvay Pharmaceuticals) in various countries, and was approved in the USA for nausea associated with chemotherapy in 1985, and in 1992 for appetite stimulation in HIV/AIDS. Oral dronabinol’s expense, variability of action, and attendant intoxication and dysphoria have limited its adoption by clinicians (Calhoun et al 1998). Two open label studies in France of oral dronabinol for chronic neuropathic pain in 7 subjects (Clermont-Gnamien et al 2002) and 8 subjects (Attal et al 2004), respectively, failed to show significant benefit on pain or other parameters, and showed adverse event frequently requiring discontinuation with doses averaging 15–16.6 mg THC. Dronabinol did demonstrate positive results in a clinical trial of multiple sclerosis pain in two measures (Svendsen et al 2004), but negative results in post-operative pain (Buggy et al 2003) (Table 1). Another uncontrolled case report in three subjects noted relief of intractable pruritus associated with cholestatic jaundice employing oral dronabinol (Neff et al 2002). Some authors have noted patient preference for whole cannabis preparations over oral THC (Joy et al 1999), and the contribution of other components beyond THC to therapeutic benefits (McPartland and Russo 2001). Inhaled THC leads to peak plasma concentration within 3–10 minutes, followed by a rapid fall while levels of intoxication are still rising, and with systemic bioavailability of 10%–35% (Grotenhermen 2004). THC absorption orally is slow and erratic with peak serum levels in 45–120 minutes or longer. Systemic bioavailability is also quite low due to rapid hepatic metabolism on first pass to 11-hydroxy-THC. A rectal suppository of THC-hemisuccinate is under investigation (Broom et al 2001), as are transdermal delivery techniques (Challapalli and Stinchcomb 2002). The terminal half-life of THC is quite prolonged due to storage in body lipids (Grotenhermen 2004).

Topicals represent a newer emerging market in medical marijuana products geared toward health and beauty. Cannabinoids can be absorbed through the skin for certain therapeutic benefits without any psychoactivity. Additionally, the essential oils in hemp and cannabis provide many benefits for skin health. From moisturizers to shampoos and deodorants, medical cannabis products continue to diversify.
^ World Health Organization.Constitution of the World Health Organization as adopted by the International Health Conference, New York, 19–22 June 1946; signed on 22 July 1946 by the representatives of 61 States (Official Records of the World Health Organization, no. 2, p. 100) and entered into force on 7 April 1948. In Grad, Frank P. (2002). "The Preamble of the Constitution of the World Health Organization". Bulletin of the World Health Organization. 80 (12): 982.

I have neuropathic pain. I’ve tried 3 brands now, this last one being less expensive. I “think” it’s helping a little bit…. maybe it’s wishful thinking. I never really knew how much to take. There is so much confusion on dosing, so I just take a dropper full now. Maybe that’s too much, maybe not. Should I take it twice a day, or once? I find it very hard to compare brand to brand. Thank you for your detailed, informative article. If anyone would care to share how much oil they take daily, I would appreciate it. I’m just trying to get a rough idea of what’s normal, an average. thanks. 

Thank you. I am 81 and started the CBD drops night and morning. I sleep better and no longer suffer the excruciating pain from diverticulitis. I saw somewhere that for my asthma I need the THC so got some (totally illegal here in South Africa). I think it is helping. The diagnosis of COPD was made some years ago and as a health psychologist I do all I can to remain healthy for my 97th birthday!! (Both my grandmother and greatgrandmother did so I believe I will too).