J Pain Manage 2016;9(4):387-394 ISSN: 1939-5914
© Nova Science Publishers, Inc.
History of medical cannabis
Andrew Hand, MSc, Alexia Blake, MSc,
Paul Kerrigan, BSc, Phineas Samuel,
and Jeremy Friedberg*, PhD
MedReleaf Corp, Markham Industrial Park, Markham,
* Correspondence: Dr. Jeremy Friedberg, MedReleaf Corp.,
Markham Industrial Park, Markham, Ontario, Canada,
L3R 6C4, P.O. Box 3040.
Understanding the cultural and medical history of cannabis
use is an important component to the successful integration
of cannabis in modern clinical practices. This chapter
chronicles over six thousand years of documented cannabis
use in cultural practices, medical applications, breeding
practices to enhance the pharmacological properties, and
the various methods by which people have consumed the
Keywords: Cannabis, history of cannabis, medical cannabis,
Today there is much discussion and debate over
cannabis and its use in healthcare. But what is often
left out of the dialogue is the more than 6000 years of
documented experience people have had with this
plant. Historically, cannabis’ medical applications
appear to have been realized by most cultures,
however, it appears that much of our modern day
cultural perspective on cannabis is based neither on
historical evidence nor recent discovery. As with
many scientific disciplines, much can be learned from
our collective history. To help with our modern
understanding of cannabis, this chapter provides the
reader with a historical account of this plant’s use, a
perspective into the effects of millennia of selective
breeding, and insight into the many ways in which
cannabis can be administered.
History of cannabis use
The earliest evidence of cannabis cultivation comes
from China in the form of pollen deposits found in the
village site of Pan-p’o dated to 4000 BCE (1). At the
Andrew Hand, Alexia Blake, Paul Kerrigan et al.
time, cannabis was regarded among the ‘five grains’
and was farmed as a major food crop in addition to its
major role in the production of textiles, rope, paper,
and oil (2). The first record of its use in medicine
comes from the Pen-ts’ao ching, the world’s oldest
pharmacopoeia (3). Although compiled between 0-
100 AD, the Pen-ts’ao has been attributed to Emperor
Shen-nung, who ruled during 2700 BCE (3). It
recognizes cannabis as being useful for more than 100
ailments, including rheumatic pain, gout and malaria
(4). The Pen-ts’ao ching also mentions the
psychoactive effects of cannabis stating that “ma-fen
(fruit of cannabis), if taken over the long-term, makes
one communicate with spirits and lightens one’s
body” (1). Between 117 and 207 AD, Hua T’o, a
physician of the time and the founder of Chinese
surgery, described cannabis as an analgesic (5). He is
reported to have used a mixture of cannabis and wine
to anesthetize his patients before surgery (1). As
cannabis use increased in China, it spread westward,
reaching India by 1000 BCE (2, 3).
Cannabis spread quickly throughout India and
was used extensively, both recreationally and
medicinally (3). It was also adopted and integrated
into religious practices, earning mention in the
Atharva Veda, one of the Vedic scriptures of
Hinduism, as being among the five sacred plants of
Hinduism, and teaching that a guardian angel lives
within its leaves (3). Cannabis is mentioned within the
Vedas as a “source of happiness,” a “joy-giver,” and a
“bringer of freedom” (2, 3). The Raja Valabba states
that the gods created cannabis out of compassion for
humans (2). In Hinduism, cannabis was smoked
during the daily devotional service (2). Due to
religious use in India, it was possible to explore the
medicinal benefits of cannabis, which led to the
discovery that cannabis can be used to treat a plethora
of diseases and ailments (2). The general uses in
India included use as an analgesic, anticonvulsant,
anesthetic, antibiotic, and anti-inflammatory (3).
These properties allowed for the treatment of many
diseases, including epilepsy, rabies, anxiety,
rheumatism and even respiratory conditions such as
bronchitis and asthma (3). Cannabis use continued to
spread throughout the world and was adopted by
many different cultures (3).
The Assyrians were aware of cannabis’
psychotropic effects since at least 900 BCE (3). By
450 BCE, cannabis had reached the Mediterranean, as
evidenced by a first-hand account from Herodotus (3).
Herodotus writes of a Scythian funeral ceremony,
where cannabis seeds were burned ritually for their
euphoric effects (3). In Tibet, cannabis was
considered to be sacred, used extensively in medicine
and in Tantric Buddhism to facilitate meditation (3).
In Persian medicine, cannabis’ biphasic effects were
clearly noted, emphasizing the distinction between
cannabis’ initial euphoric effects and the dysphoric
effects that follow (2). The Persian physician
Avicenna (980 – 1037 AD), one of the most
influential medical writers of the medieval period,
published ‘Avicenna’s Canon of Medicine’, a
summary of all medical knowledge of the time (6).
His canon was widely studied in western medicine
from the thirteenth to the nineteenth century, having a
lasting impact on western medicine (6). Avicenna
recorded cannabis as an effective treatment for gout,
edema, infectious wounds and severe headaches (6).
In Arabic medicine, cannabis was regarded as an
effective treatment for epilepsy (7). Recorded first by
al-Mayusi, between 900-1000 AD (13), followed by
al-Badri, in 1464 AD, who wrote of the chamberlain’s
epileptic son who was cured using cannabis leaves
(6). In the 1300s, Arab traders brought cannabis from
India to Africa, where it was used to treat malaria,
fever, asthma and dysentery (3). The 1500s saw
cannabis reach South America via the slave trade,
which transported Africans along with seeds, from
Angola to Brazil (3). In Brazil, cannabis was used
extensively in the African community, including in
religious rituals such as the ‘Catimbo,’ which used
cannabis for magical and medical purposes. From
Brazil, cannabis travelled north to Mexico where it
was used recreationally by individuals of low-
socioeconomic class (3).
Cannabis’ therapeutic uses were first introduced
to Western medicine in 1839, when the Irish
physician William O’Shaughnessy published ‘On the
preparations of Indian hemp, or gunjah’ (3). In the
first paragraph of his work he highlights that “…in
Western Europe, [cannabis’] use either as a
stimulant or as a remedy is equally unknown,”
indicating British unfamiliarity with the drug (3).
O’Shaughnessy first encountered cannabis while
working as a physician in India with the British East
India Company (3). Interested, he studied the existing
History and cannabis
literature on cannabis and conferred with elders and
healers to understand the recreational and medicinal
uses of cannabis in India (3). O’Shaughnessy then
proceeded to test the effects of different forms of
cannabis on animals to evaluate the toxicity of the
drug (3). Confident that the drug was safe, he
provided extracts of cannabis to patients and
discovered it had both analgesic and sedative
properties (5). The immediate results impressed him
enough to begin prescribing the drug and he was
rewarded with positive results (5). His greatest
success came when he managed to calm the muscle
spasms caused by tetanus and rabies (5).
O’Shaughnessy’s initial results, followed by those of
other physicians, led cannabis to spread rapidly
through Western medicine in both Europe and into
In 1860, the Committee on Cannabis Indica of the
Ohio State Medical Society reported success for the
use of cannabis to treat many ailments including
gonorrhea, asthma, rheumatism and intense stomach
pain (9). Cannabis’ use in medicine continued to
grow, peaking in the late eighteenth/early nineteenth
century when it could be readily found in over-the-
counter pharmaceuticals such as “Piso’s cure” and the
“One day cough cure” (5). This rapidly increasing
popularity of the new medication sparked the
publication of more than 100 papers on its therapeutic
uses (3). In 1924, Sajous’s Analytic Cyclopedia of
Practical Medicine summarized what, at the time,
were believed to be the main therapeutic uses of
cannabis (10). They concluded that cannabis was
useful in the treatment of migraines, coughing and
inflammation, along with diseases such as tetanus,
rabies, and gonorrhea.
Following this rapid rise of use within 1900s
medicine, cannabis use began to decline due to a
variety of factors (3). Vaccines for diseases such as
tetanus made cannabis’ previous role in treating these
diseases obsolete (3). Furthermore, development of
synthetic analgesics such as chloral hydrate,
antipyrine (5) and aspirin filled some of the demand
for analgesics (3). However, it was the development
of the hypodermic needle and its application to
opiates that could be considered the greatest factor to
the decline of cannabis use (3). These factors led to an
overall decrease in the prevalence of cannabis and its
necessity as an analgesic, making it more susceptible
to the political influences to follow.
At the beginning of the 1900s, cannabis’
recreational use in the United States of America was
in large restricted to Mexican and African minority
groups who had immigrated into the country (3). By
the 1930s there was an increase in recreational use
among all US citizens, leading narcotics officers to
push for restrictive legislation on both the recreational
and medicinal use of cannabis (5). The American
Medical Association advised that cannabis remains a
medical agent, citing its medicinal use, low toxicity
and absolutely no evidence “…to show that its
medicinal use is leading to the development of
cannabis addiction” (5). However, despite the
protests, in 1937 the Marijuana Tax Act was enacted,
essentially ending the already diminished use of
cannabis as a therapeutic (5). In 1941, cannabis was
removed entirely from the American pharmacopeia
(5). Over the next couple decades, cannabis use in
medicine was essentially non-existent, and it was not
until the 1970s that medical interests were revived (5).
The prevalence of recreational cannabis use rose
significantly in the early 1970s, spiking from only 5%
of people reporting to have used cannabis in 1967, to
44% in 1971 (3). This massive increase in recreational
use brought cannabis into the spotlight, and with the
discovery of cannabis’ active component (Δ9-THC)
by Gaoni and Mechoulam in 1964, it became possible
to isolate the principle component, making the study
and quantification of its effects possible (3). In 1988,
the receptor CB1 was identified (11). It was found to
be the binding site of THC and to be the most
abundant neurotransmitter receptor in the central
nervous system (11). This discovery was followed by
the identification of a second cannabinoid receptor,
CB2, localized primarily in the peripheral nervous
system and on immune cells (12). The presence of
cannabinoid receptors, concentrated in neural and
immune cells, alluded to a possible mode of action
that could be the source of cannabis’ analgesic,
sedative and immunoregulatory properties.
Over the past few thousand years many different
cultures have been exposed to cannabis and often
realized the medicinal application of cannabis (see
Figure 1). When cannabis was introduced to Western
medicine, its medicinal applications were swiftly
recognized and its use spread rapidly. The decline of
Andrew Hand, Alexia Blake, Paul Kerrigan et al.
cannabis use in the west was due to a variety of
factors and as a result its medicinal use was forgotten.
The discovery of the active constituent Δ9-THC, as
well as endogenous receptors for cannabinoids,
stimulated research into the drug shows that cannabis
does, in fact, have a direct effect on the body.
Figure 1. A timeline of cultural and medical milestones in cannabis.
The genetics and selective breeding
Since human cultures first began cultivating cannabis,
selective breeding has been employed to improve wild
cannabis as a source of seeds, fiber and drugs.
However, cannabis is not a very simple plant to breed,
as two primary complications have made controlled
selective breeding a challenge. Firstly, cannabis is
typically a dioecious plant, indicating that individual
plants are distinctly male or female. Therefore,
cannabis plants are predisposed to outcrossing as
opposed to self-pollination, which is the primary
means of fixing desirable traits in other species. In
addition to this, the valuable components of cannabis
are produced and harvested from female plants, and
thus it is a challenge to identify males with favourable
genetically regulated traits. Secondly, cannabis is a
wind-pollinated plant and therefore will very easily
pollinate surrounding females, making selective
crosses difficult to control. Due to the challenges
outlined above, it is typical of cannabis growers to
utilize clonal propagation as opposed to seeds, as this
will produce identical “offspring.” Regardless of these
limitations, cannabis breeders have improved upon
the concentration of psychotropic compounds and
yield, whereas hemp breeders have continuously
worked to improve the textile characteristics of fiber-
type cannabis cultivars. Understanding the inheritance
of chemical phenotype (chemotype) for the most
clinically relevant cannabinoids has been central to
modern medicinal cannabis and hemp breeding.
Modern molecular techniques have allowed for a
History and cannabis
greater ability to screen for elite cultivars, greatly
increasing the rate at which desired traits can be
identified and bred into new cultivated varieties.
Primarily through the research of de Meijer at
HortaPharm B.V., four loci, O, A, B and C, have been
found to genetically regulate cannabinoid content (13,
14). Cannabinoids are terpenophenolic compounds,
produced primarily with the monoterpenoid precursor
geranylpyrophosphate (GPP), and one of two phenolic
precursors, olivetolic acid or divarinolic acid, both of
which are resorcinolic acid homologs produced by the
polyketide pathway (15, 16). Production of the
phenolic precursors can be disrupted by a mutant null
allele o, at locus O. In a homozygous state, synthesis
of either resorcinolic acid precursor is blocked, while
O/o heterozygous phenotypes typically have one-tenth
the cannabinoid content. This indicates that allele o
acts as a dominant repressor of the polyketide
pathway that generates both olivetolic acid and
divarinolic acid (17).
Synthesis of either olivetolic acid or divarinolic
acid is regulated by locus A, which according to de
Meijer (18) is likely polygenic, with the alleles Ape1 to
n encoding olivetolic acid synthase, and alleles Apr1 to n
encoding divarinolic acid synthase. These phenolic
precursors, along with GPP, are utilized by the
enzyme geranylpyrophosphate:olivetolate transferase
to produce either CBGA or CBGVA depending on the
phenolic precursor present (19). The synthesis of the
two most clinically relevant cannabinoids, THC
and CBD, is then controlled by co-dominant
alleles present at Locus B. THCA/THCVA or
CBDA/CBDVA will be produced if alleles BT or BD
is present and functional, respectively, while
homozygous individuals will produce significant
quantities of both metabolites. Variations in the
sequence of BT and BD can lead to enzymes with
reduced function, so THC:CBD ratios are commonly
found to deviate from 1:1 (14). Mutant alleles
BT0 and BD0 significantly reduce THCA and
CBDA production, while leading to considerable
accumulation of the precursor CBGA (14). Lastly, an
independent gene at Locus C produces the enzyme
CBCA synthase, which competes with CBDA
synthase and THCA synthase for CBGA precursor,
producing the cannabinoid CBCA or CBCVA (see
Figure 2. Cannabinoids biosynthetic pathways.
Andrew Hand, Alexia Blake, Paul Kerrigan et al.
Many of the genes mentioned above have been
sequenced, and molecular markers detectable via PCR
have been developed and validated to correlate with
specific chemotypes. Modern breeders can take
advantage of this simple molecular technique in order
to expedite breeding objectives, while using classical
breeding techniques in order to select for other
favourable traits, such as yield, disease resistance and
flowering time requirements, all aspects that greatly
impact the output of a medical cannabis facility.
In the near future, more advanced molecular
breeding techniques, such as transgenic gene
expression or substitution of gene promoters with
knockdown/overexpression variants could yield
dramatically different chemotypes with potentially
novel medical applications.
Modern methods of cannabis
Most commonly, the flower of the plant is dried,
ground, and smoked. The main benefit of smoking is
that it provides rapid relief on the timescale of
minutes (20). Furthermore, this instant feedback
allows users to adjust their dosing to either increase or
maintain a steady state of relief. This control also
reduces the risk of experiencing adverse effects due to
overconsumption, such as dizziness, paranoia, or
Similarly, vaporization also provides rapid
onset of effects, with the added benefit of being
considered a much safer and more efficient means
of cannabis consumption compared to smoking.
Pyrolysis of cannabis has been shown to generate
more than 2000 new compounds, including
hazardous components such as carbon monoxide
and polycyclic aromatic hydrocarbons (21, 22).
In addition, some studies have shown that 30-50%
of THC is lost during burning (23). Since vaporization
involves heating dried cannabis to temperatures
below combustion, the production of smoke is
avoided, and fewer harmful combustion by-products
are created (24, 25). Thus, vaporization is a very
efficient method of consumption that allows for rapid
relief of symptoms, and is overall a superior and
healthier means of consuming cannabis compared to
Oral administration through either ingestion or
sublingual absorption are also popular methods of
cannabis consumption. Similar to vaporization, oral
consumption avoids exposure to smoke and other
hazardous pyrolysis by-products. However, cannabis
must be decarboxylated prior to ingestion.
Oral administration often involves the
consumption of a cannabis extract rather than
the actual plant material. For oral sprays, such as
Sativex, the extract is often mixed with a
diluting/carrier agent, such as propylene glycol (26).
Alcohol, flavouring, and sweeteners may also be
added to adjust the viscosity and taste. Application of
the product under the tongue results in rapid
absorption due to the high vascularity of the
sublingual region. However, taste is obviously a
concern with such products, and a titrated spray
dispenser is required for consistent dosing.
Alternatively, an infusion can be made by
soaking decarboxylated cannabis in butter or edible
oil. This infusion can be used for cooking or baking
applications. However, making this infusion is a time-
consuming and highly tedious process that, if
completed at home, will produce extracts with
unknown and highly variable THC concentrations.
Because of this dosing challenge, capsules may be a
safer and more convenient method of cannabis
administration, resulting in higher patient compliance
and a lower risk of experiencing adverse effects.
Despite being a popular historical method of
consuming cannabis, tea preparations are not very
popular or recommended for several reasons (27).
First, cannabinoid extraction during steeping will be
very low due to the low water solubility of
cannabinoids. However, the addition of cream or non-
skim milk may aid in this. Secondly, water
temperatures may not be sufficient to completely
decarboxylate cannabinoids. Thirdly, the final
concentration of cannabinoids in the tea will be
unknown (and low), making tea a very inefficient way
of consuming cannabis.
Compared to sublingual administration or
inhalation, there is a noticeable delay in the onset of
therapeutic action following ingestion (21, 28). For
this reason, ingestion may not be a preferred means of
consumption if instant relief is desired.
History and cannabis
Other methods of consumption
While inhalation and oral administration are the most
common (and therefore the most studied) methods of
cannabis consumption, rectal, transdermal, and
ophthalmological administration are also possible. All
of these methods are commonly used for drugs that
are not suitable for oral administration, often due
to their potential to irritate the stomach or
gastrointestinal tract, and more commonly due to their
low oral bioavailability (21). For cannabis, these
methods also avoid the generation and consumption
of smoke and other hazardous combustion
Transdermal application may be achieved by
incorporating decarboxylated cannabis oil into topical
products, such as lotions, gels, or transdermal
patches. Such products may be most useful for
individuals seeking to treat localized, physical
pain. Ophthalmological and suppository products
are less common, but animal studies have
demonstrated their potential as alternative methods
of cannabis consumption offering rapid absorption
Cannabis use both culturally and medically has
had a long and well-documented history. Cannabis
has been used medicinally in many different
cultures, and upon exposure to western medicine
in the 19th century, it quickly gained popularity
as an analgesic, anticonvulsive, and hypnotic. These
medical properties are innately part of cannabis
biology, and over time selective breeding projects
have amplified these traits. The medical properties
of this plant combined with an understanding
of the effective methods of consumption help
make cannabis the powerful medication it is
today. Much can be learned from this historical
record, but what is most salient is that the use
of cannabis to treat clinical symptoms is not new.
The challenge is education and policy changes to
incorporate the nature of cannabis’ atypical
consumption requirements into modern clinical
Conflict of interest
The authors are all employees of MedReleaf, an
authorized grower and distributor of medical cannabis
We thank Dean Pelkonen for assistance with graphic
design for Figure 1.
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Submitted: August 01, 2016. Revised: August 25,
2016.Accepted: September 03, 2016.