Medical cannabis

[6][7] Regarding non-inhaled cannabis or cannabinoids, a 2021 review found that it provided little relief against chronic pain and sleep disturbance, and caused several transient adverse effects, such as cognitive impairment, nausea, and drowsiness.

[9] Some American medical organizations have requested removal of cannabis from the list of Schedule I controlled substances, emphasizing that rescheduling would enable more extensive research and regulatory oversight to ensure safe access.

Countries that allow the medical use of whole-plant cannabis include Argentina, Australia, Canada, Chile, Colombia, Germany, Greece, Israel, Italy, the Netherlands, Peru, Poland, Portugal, Spain, and Uruguay.

In the U.S., the National Institute on Drug Abuse defines medical cannabis as "using the whole, unprocessed marijuana plant or its basic extracts to treat symptoms of illness and other conditions".

[17] Overall, research into the health effects of medical cannabis has been of low quality and it is not clear whether it is a useful treatment for any condition, or whether harms outweigh any benefit.

[20] It is unclear whether American states might be able to mitigate the adverse effects of the opioid epidemic by prescribing medical cannabis as an alternative pain management drug.

[22] Research analyzing data from the National Health and Nutrition Examination Survey (NHANES) did not find significant differences in sleep duration between cannabis users and non-users.

CBD, a non-psychoactive component of cannabis, is of particular interest due to its potential to influence sleep without the psychoactive effects associated with tetrahydrocannabinol (THC).

[29] A 2016 Cochrane review said that cannabinoids were "probably effective" in treating chemotherapy-induced nausea in children, but with a high side-effect profile (mainly drowsiness, dizziness, altered moods, and increased appetite).

Less common side effects were "ocular problems, orthostatic hypotension, muscle twitching, pruritus, vagueness, hallucinations, lightheadedness and dry mouth".

However, the relationship between cannabis use and anxiety symptoms is complex, and while some users report relief, the overall evidence from observational studies and clinical trials remains inconclusive.

[40][41] Cannabis use, especially at high doses, is associated with a higher risk of psychosis, particularly in individuals with a genetic predisposition to psychotic disorders like schizophrenia.

As of 2021[update] there is a lack of research into long-term cognitive effects of medical use of cannabis, but one 12-month observational study reported that "MC patients demonstrated significant improvements on measures of executive function and clinical state over the course of 12 months".

Oral administration has the lowest bioavailability of approximately 6%, variable absorption depending on the vehicle used, and the longest time to peak plasma levels (2 to 6 hours) compared to smoked or vaporized THC.

[61] THC further distributes into fatty tissues a few days after administration due to its high lipophilicity, and is found deposited in the spleen and fat after redistribution.

[6] It is difficult to predict the pharmacological response to cannabis because concentration of cannabinoids varies widely, as there are different ways of preparing it for consumption (smoked, applied as oils, eaten, infused into other foods, or drunk) and a lack of production controls.

[71] Cannabis vaporizers have gained popularity because of a perception among users that fewer harmful chemicals are ingested when components are inhaled via aerosol rather than smoke.

[6] Oral preparations are "problematic due to the uptake of cannabinoids into fatty tissue, from which they are released slowly, and the significant first-pass liver metabolism, which breaks down Δ9THC and contributes further to the variability of plasma concentrations".

[71] The US Food and Drug Administration (FDA) has not approved smoked cannabis for any condition or disease, as it deems that evidence is lacking concerning safety and efficacy.

[80] In the medieval Islamic world, Arabic physicians made use of the diuretic, antiemetic, antiepileptic, anti-inflammatory, analgesic and antipyretic properties of Cannabis sativa, and used it extensively as medication from the 8th to 18th centuries.

Widely cultivated strains of cannabis, such as "Afghani" or "Hindu Kush", are indigenous to the Pakistan and Afghanistan regions, while "Durban Poison" is native to Africa.

[85] O'Shaughnessy discovered cannabis in the 1830s while living abroad in India, where he conducted numerous experiments investigating the drug's medical utility (noting in particular its analgesic and anticonvulsant effects).

[89] The use of cannabis in medicine began to decline by the end of the 19th century, due to difficulty in controlling dosages and the rise in popularity of synthetic and opium-derived drugs.

[87] Cannabis began to attract renewed interest as medicine in the 1970s and 1980s, in particular due to its use by cancer and AIDS patients who reported relief from the effects of chemotherapy and wasting syndrome.

[93] Countries that have legalized the medical use of cannabis include Argentina,[94] Australia,[95] Brazil,[96] Canada,[97] Chile,[97] Colombia,[97] Costa Rica,[98] Croatia,[99] Cyprus,[100] Czech Republic,[97] Finland,[101] Germany,[102] Greece,[103] Israel,[104] Italy,[105] Jamaica,[106] Lebanon,[107] Luxembourg,[108] Malta,[109] Morocco,[110] the Netherlands,[97] New Zealand,[111] North Macedonia,[112] Panama,[113] Peru,[114] Poland,[115] Portugal,[116] Rwanda,[117] Sri Lanka,[118] Switzerland,[119] Thailand,[120] the United Kingdom,[121] and Uruguay.

[13] Cannabis remains illegal at the federal level under the Controlled Substances Act, which classifies it as a Schedule I drug with a high potential for abuse and no accepted medical use.

[139] In 2014, the startup Meadow began offering on-demand delivery of medical marijuana in the San Francisco Bay Area, through their mobile app.

[141] In the United States, health insurance companies may not pay for a medical marijuana prescription as the Food and Drug Administration must approve any substance for medicinal purposes.

[142] However, the New Mexico Court of Appeals has ruled that workers' compensation insurance must pay for prescribed marijuana as part of the state's Medical Cannabis Program.

[162] Relative to inhaled consumption, peak concentration of oral THC is delayed, and it may be difficult to determine optimal dosage because of variability in patient absorption.