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The history of medical cannabis: From ancient remedies to today

The history of cannabis in medicine goes back thousands of years. The story of medical cannabis is a compelling journey that spans millennia, cultures, and continents, involving ancient remedies, scientific discovery, and societal shifts that have ultimately brought this back into the spotlight as a recognised medicine.

Ancient cannabis use in medicine

  • The earliest confirmed fossil of cannabis pollen dates back 19.6 million years and was found in northeastern China. However, studies suggest that cannabis may have diverged from its nearest ancestor up to 28 million years ago in the same region of China.
  • Interaction with the cannabis plant, particularly hemp, began around 12,000 years ago, with the first evidence of its domestication by ancient Chinese societies in areas of Asia, including what is now modern-day Japan, Korea, and India. The clearest evidence of its cultivation in China dates back to around 4000 BC.
  • Its medicinal properties were documented for the Chinese Emperor Shen Nung in a text dated to 2737 B.C.
  • The Chinese term ma, used to describe medical cannabis by 2700 BCE, is the oldest recorded name for the hemp plant.
  • One of the earliest recorded uses of cannabis for epilepsy comes from Babylonia, between 718 and 612 BC, highlighting its long-standing application in neurological conditions.
  • Medical texts from Indian Hindus, the Greco-Roman Empire, and the Islamic Golden Age reported cannabis as a remedy for various health problems, including inflammation, pain, and epilepsy.

Early cannabis use in Western medicine

  • Irish physician William O’Shaughnessy published a monograph on Indian hemp in 1839. In 1842, he brought a quantity of cannabis with him from India to Britain, which led to the publication of a key paper in the journal that would later become the British Medical Journal.
  • O’Shaughnessy described potential therapeutic benefits of cannabis and reported it to be a useful anti-convulsant in cases of tetanus. He also studied its effects in rheumatism, hydrophobia, and cholera, finding little effect.
  • Use of medical cannabis became more common across Europe and North America by the end of the 19th century.

Prohibition: The fall of cannabis

  • The medical use of cannabis started to decline with the advent of synthetic drugs. This was accelerated by a period of prohibition.
  • In the US, state-level restrictions began as early as 1911, culminating in federal prohibition with the Marihuana Tax Act of 1937. Sensationalist news stories and political campaigns helped to create a public perception of cannabis as a dangerous drug.
  • In the UK, the Dangerous Drugs Act 1920 amendment was the first step in controlling the substance. However, medical cannabis could still be prescribed by doctors until the Misuse of Drugs Act in 1971. Under this new legislation, cannabis was re-classified as a Schedule 1 controlled substance, meaning it was considered to have no recognised medicinal use. It was also listed as a Class B drug alongside codeine, ketamine and ‘spice’, despite a temporary reclassification to Class C in the 2000s.

Scientific breakthrough and the resurgence of medical cannabis

  • Despite prohibition, scientific advancements quietly continued. The work of Professor Raphael Mechoulam was instrumental in defining the structure and chemistry of cannabidiol (CBD) in 1963. The following year, in 1964, Δ9-tetrahydrocannabinol (Δ9-THC) was also isolated by Professor Mechoulam and his team.
  • The early 1990s marked significant breakthroughs, including the cloning of the cannabinoid type 1 (CB1) and type 2 (CB2) receptors, as well as the discovery of our body’s own endocannabinoid system (ECS), which fundamentally shifted our understanding and opened up new avenues for research.
  • Medical cannabis was legalised in California in 1996 and Canada in 2001.
  • Medical cannabis in the UK was changed from Schedule 1 to Schedule 2 in 2018, officially recognising its medicinal value in UK legislation and enabling specialist doctors to prescribe it.
  • Across Europe, similar changes have unfolded, with countries like Poland, Switzerland, and Ukraine legalising or expanding access.

Cannabis in Western medicine today

  • Today, we are in the midst of a global resurgence in medical cannabis, driven by scientific understanding and patient advocacy.

Timeline graphic:

19.6 Million BC – Oldest recorded fossil of cannabis pollen

10,000 BC – The earliest believed cultivation of cannabis by human civilisations

4,000 BC – First recorded cultivation of hemp

2,737 BC – Earliest record of cannabis as a medicine in China

1000 BC – Widespread use of cannabis as a medicine in India

718‒612 BC – Earliest recorded use of cannabis for epilepsy in Babylonia

1st century AD – Writings by ancient Greeks highlight the medicinal properties of cannabis

1025 AD – Ancient Persian text suggests cannabis as a treatment for headache, gout, and infectious wounds

1839-43 – William O’Shaughnessy records the therapeutic and anti-convulsant properties of cannabis in a published monograph on Indian hemp and subsequent scientific publication on its effect on seizures.

1937 – Marihuana Tax Act bans the use of cannabis in the US

1964 – Cannabidiol (CBD) structure and chemistry is identified

1964 – Δ9-tetrahydrocannabinol (Δ9-THC) is first isolated

1971 – Misuse of Drugs Act in the UK reclassifies cannabis as a Schedule 1 substance

1988-1995 – Discovery of CB1 and CB2 receptors and other components of the endocannabinoid system.

1996-present day – Following California in 1996 and Canada in 2001, countries across Europe have legalised and expanded the use of medical cannabis

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