In the mid 19th century, medical interest in the use of cannabis began to grow in the West. The advent of the syringe and injectable medicines contributed to an eventual decline in the popularity of cannabis for therapeutic uses, as did the invention of new drugs such as
aspirin. An Irish physician,
William Brooke O'Shaughnessy, is credited with introducing the therapeutic use of cannabis to Western medicine in English-speaking countries. He was Assistant-Surgeon and Professor of Chemistry at the Medical College of
Calcutta, and conducted a cannabis experiment in the 1830s, first testing his preparations on animals, then administering them to patients to help treat muscle spasms, stomach cramps or general pain. Modern medical and scientific inquiry began with doctors like
O'Shaughnessy and
Moreau de Tours, who used it to treat
melancholia and
migraines, and as a sleeping aid, analgesic and
anticonvulsant. At the local level, authorities introduced various laws which required preparations containing cannabis and were to be sold
over the counter must be marked with warning labels under the so-called poison laws. In 1905
Samuel Hopkins Adams published an exposé entitled "
The Great American Fraud" in ''
Collier's Weekly'' about the
patent medicines that led to the passage of the first
Pure Food and Drug Act in 1906. This
statute did not ban alcohol, narcotics, and stimulants in the medicines; rather, it required medicinal products to be labeled as such and curbed some of the more misleading, overstated, or
fraudulent claims that previously appeared on labels. At the turn of the 20th century the Scandinavian
maltose- and cannabis-based drink
Maltos-Cannabis was widely available in Denmark and Norway. Promoted as "an excellent lunch drink, especially for children and young people", the product had won a prize at the
Exposition Internationale d'Anvers in 1894. Later in the century, researchers investigating methods of detecting cannabis intoxication discovered that smoking the drug reduced
intraocular pressure. In 1955 the antibacterial effects were described at the
Palacký University of Olomouc. Since 1971
Lumír Ondřej Hanuš was growing cannabis for his scientific research on two large fields in authority of the university. The marijuana extracts were then used at the university hospital as a cure for aphthae and haze. In 1973 physician
Tod H. Mikuriya reignited the debate concerning cannabis as medicine when he published "Marijuana Medical Papers". High intraocular pressure causes blindness in
glaucoma patients, so he hypothesized that using the drug could prevent blindness in patients. Many
Vietnam War veterans also found that the drug prevented muscle spasms caused by spinal injuries suffered in battle. In 1964, Dr. Albert Lockhart and
Manley West began studying the health effects of traditional cannabis use in
Jamaican communities. They discovered that
Rastafarians had unusually low glaucoma rates and local fishermen were washing their eyes with cannabis extract in the belief that it would improve their sight. Lockhart and West developed, and in 1987 gained permission to market, the pharmaceutical
Canasol: one of the first cannabis extracts. They continued to work with cannabis, developing more pharmaceuticals and eventually receiving the
Jamaican Order of Merit for their work.
Canada The medicinal use of cannabis became legal in Canada in 2001, though was not increasingly popularized until about 13 years later in 2014. It became more popular after the regulations were updated and the diagnosing physicians were able to diagnose specific amounts and dosages for up to a 30-day supply.
United States In the 1970s, a
synthetic version of
THC was produced and approved for use in the United States as the drug
Marinol. It was delivered as a capsule, to be swallowed. Patients complained that the violent nausea associated with chemotherapy made swallowing capsules difficult. Further, along with ingested cannabis, capsules are harder to
dose-titrate accurately than smoked cannabis because their onset of action is so much slower. Smoking has remained the route of choice for many patients because its onset of action provides almost immediate relief from symptoms and because that fast onset greatly simplifies titration. For these reasons, and because of the difficulties arising from the way cannabinoids are metabolized after being ingested, oral dosing is probably the least satisfactory route for cannabis administration.
Robert Randall of the United States successfully used a
medical necessity defense when he was charged with illegal possession of cannabis to treat his
glaucoma. The case,
United States v. Randall (1976), is "The first successful articulation of the medical necessity defense in the history of the common law, and indeed, the first case to extend the necessity defense to the crimes of possession or cultivation of marijuana". Voters in eight U.S. states showed their support for cannabis prescriptions or recommendations given by physicians between 1996 and 1999, including Alaska, Arizona, California, Colorado, Maine, Michigan, Nevada, Oregon, and Washington, going against policies of the federal government. In May 2001, "The Chronic Cannabis Use in the
Compassionate Investigational New Drug Program: An Examination of Benefits and Adverse Effects of Legal Clinical Cannabis" (Russo, Mathre, Byrne et al.) was completed. This three-day examination of major body functions of four of the five living US federal cannabis patients found "mild
pulmonary changes" in two patients. In several medical marijuana cases, the patients' physician has been willing to state to the court that the patient's condition requires this medicine and so the court should not interfere. However, the
US Supreme Court outrightly rejected that defense in the landmark case ''
United States v. Oakland Cannabis Buyers' Cooperative (2001) which ruled that there is no medical necessity exception to drug laws and that the federal government is free to raid, arrest, prosecute, and imprison patients who are using medical marijuana no matter if the medicine is crucially necessary to them. On the other hand, in Gonzales v. Raich'' (2005), the
Ninth Circuit Court of Appeals told a patient in extreme pain that state law allowing medical use could not be relied on, but if arrested, the user could seek to use medical necessity as a defence. In
Maryland, a bill signed by Governor
Robert Ehrlich became law in 2003 to permit patients to use medical necessity defense to marijuana possession in the state. The maximum penalty for such users cannot exceed $100. However, the law does not prevent federal prosecution of patients since the federal law does not recognize medical necessity. Among the more than 108,000 persons in Colorado who in 2012 had received a certificate to use marijuana for medical purposes, 94% said that severe pain was the reason for the requested certificate, followed by 3% for cancer and 1% for HIV/Aids. The typical card holder was a 41-year-old male. Twelve doctors had issued 50% of the certificates. Opponents of the card system claim that most card holders are drug abusers who are faking or exaggerating their illnesses; three-fourths male patients is not the normal pattern for pain patients, it is the normal pattern for drug addicts, claim the critics. As of early 2024, 34 of the 50 US states have legalized the medical use of cannabis. Medical cannabis was further legalized with the
Removal of cannabis from Schedule I of the Controlled Substances Act in April, 2026. The
Medical Marijuana Dispensary Registration Portal was set up by the U.S.
Drug Enforcement Administration a few days later. == See also ==