Cannabis sativa - My Journey with this Herb

Published in 'The Herbalist' Journal. Vol.10 number 2, Autumn 2017

 In this article, I will give an overview of the recent use of Cannabis sativa as a plant medicine.

Much of the research work done on Cannabis, is by pharmaceutical research agencies who are prone to isolating chemicals within the plant, and this does not always gel with the way many herbalists prefer to work. As a herbalist, I see the limitations of isolated extracts and standardized herbal products. However, in the case of Cannabis, the picture is complicated by the legal status of the plant, and its use as a psychoactive recreational drug and its psychoactive effect as a medicinal plant. Removing the psychoactive component has enabled to plant to be considered to have greater potential therapeutically. It is sometimes suggested to me by patients that it is the non-psychoactive parts that are the medicinal part. This is not true, and the picture is much more complex, which I will try and explain in this article. 

In the five years that I studied Herbal Medicine at university, Cannabis was only mentioned twice as a medicine. Once in my Middlesex Chinese Medicine course the seeds were mentioned as a bulk laxative for the elderly. At Westminster University’s Western Herbalism course the pressed seed oil was mentioned as something to add to creams. These applications both use hemp, which is Cannabis sativa, mostly grown on a field scale for seeds (hemp oil), and fibre for clothes, paper, building materials and recently to process into CBD oil.

The other forms of Cannabis sativa grown for their medicinal flowers, are also known as Cannabis sativa (indica). These contain currently illegal amounts of the cannabinoid tetrahydrocannabinol (THC). This psychoactive form of the herb can be differentiated botanically into Indica, Sativa or Ruderalis depending on their growth patterns. Traditionally Indicas and Sativas have been thought to produce different cerebral effects. Indica are short and squat plants usually grown in temperate regions in a shorter growing season. Their effects are more sedating and relaxing. Cannabis sativa growing generally closer to the equator, with a longer season, is taller (closer in form to Hemp), and its effects are more stimulating cerebrally, hence more anti-depressant but more likely to cause anxiety. Many strains grown today are hybrids of indica/sativa, and combine the growth characteristics and cerebral effects of the two. The difference between Hemp (Cannabis sativa) and Cannabis grown for the medicinal flowers (Indica/Sativa) is one of selective breeding, over millennia, and that flowers do not produce many Cannabinoids (e.g. THC / CBD) in colder climates such as the UK.

It is surprising, that Cannabis sativa (indica) wasn't mentioned in the herbal degrees I studied on, as it was prescribed by doctors in the UK from the 1840’s up until 1971.

Irish physician William Brooke O'Shaughnessy, who had studied the drug while working as a medical officer in Bengal with the East India company, brought a quantity of cannabis with him on his return to Britain in 1842. A plethora of medical papers were published on the drug right through the Victorian age. Queen Victoria’s personal physician published several these, which is why it is presumed that Victoria may have been prescribed it. As alkaloids were isolated and synthesized in the early twentieth century, Cannabis quickly became unfashionable drug to use. Having a non-alkaloid mode of action, it could not be standardized, and it gathered a reputation as a drug of recreational use.


California has this year voted to legalise Cannabis, as a recreational drug/herb. It has been legal for 20 years in California as a medicine. This means that if a patient has a condition that fits the list of known diseases that are eased by the herb, then they can take their prescription card into any Cannabis dispensary and choose a strain of herb, dispensed in dry herb form, tincture, oil, topical products and dermal patches. The range of conditions it can be prescribed for are: Anxiety, Arthritis, Cancer, Chemotherapy Side Effects, Chronic Pain, Depression, Fibromyalgia, Glaucoma, HIV-AIDS, Migraine Headaches, Multiple Sclerosis, Radiation Therapy Side Effects. And, “any other chronic or persistent medical symptom that substantially limits the ability of the person to conduct one or more major life activities (as defined by the Americans with Disabilities Act of 1990) or, if not alleviated, may cause serious harm to the patient's safety or physical or mental health.” 

The herb is now legal for medicinal use in over half of the states in the USA, and nearly half of the countries in the EU.

 It is currently legally prescribed in the UK, licensed as the drug Sativex. Prescribed for spasticity in Multiple Sclerosis, it is also available on private prescription for neuropathic pain, when other drugs are not sufficiently helping.  GW pharmaceuticals who manufacture Sativex, are also developing Cannabis based drugs and are running stage 2 clinical trials for childhood epilepsy and schizophrenia. Stage 3 trials for Glioma (rare malignant brain tumour). These are not synthesized compounds of the herb but isolated extracts, either a 1:1 THC: CBD ratio for Sativex and Glioma, or pure CBD for epilepsy and schizophrenia.

 The breadth of clinical applications for Cannabis is huge. A wealth of scientific research has been done on the herb and its isolated cannabinoids for over 160 years. The International Cannabinoid Research Society (ICRS) has been organising annual conferences since 1990. For an idea of the wealth of scientific papers dedicated to his herb look at . Collated by a retired nurse it is a work of great dedication. There are many 1000’s of medical studies listed.

So, you may be asking, “How can this psychoactive plant have benefit for childhood epilepsy and schizophrenia, when a known side effect of Cannabis use is Psychosis?” This is possible because the main active constituents of Cannabis - the Cannabinoids - can be isolated or concentrated, either in a laboratory, or by plant breeding techniques. The term skunk comes from selective plant breeding, resulting in a flower with high levels of the psychoactive Delta9-tetrahydrocannabinol (THC) and corresponding low levels of the calming and antipsychotic Cannabidiol (CBD). Most of the flowers grown in the UK for the recreational market fit this skunk pattern.  Wild grown strains are more likely to have a more balanced THC/ CBD ratio. Some plant breeders in decriminalised countries are increasing levels of CBD into the plants, particularly for the medical market. Medical users in the UK who grow their own medicine are doing the same.  CBD can also be extracted from non-psychoactive hemp plants, grown in the UK and globally. This is legally sold in the UK, and quality varies dramatically, including the amount of CBD found in the same volume of medicine. E.g. 30mg of CBD might be found in 10 ml of the CBD oil, and in another product 1000mg of CBD could be found in 10 ml of the oil. CBD can also be extracted from the flowers of certain selectively bred plants which have very high levels of CBD and low (but illegal levels of THC). These are considered superior to Hemp based CBD products because they also contain the essential oils found in the flowers, of non-hemp flowers which are considered to create an entourage effect with the cannabinoids and be therapeutically superior. But these CBD flower based products are not readily available in the UK because the legal limit for THC is so low (0.05%), and not many European suppliers have the technology to extract the THC out of the products, to allow them to be legal. Many patients would also wish to not have any THC in their products. Therefore, Hemp based CBD proliferates the European markets.  CBD from Hemp based products is extracted from the whole plant grown on a field scale. A paste is extracted which contains roughly 8-12% CBD and this can be further processed or diluted into a carrier oil. As hemp is a bio-accumulator it is imperative that hemp based CBD comes from organic agriculture,

There are 113 different cannabinoids found in the plant. THC and CBD are the most abundant and the most researched.

THC or its precise isomer (−)-trans-Δ9-tetrahydrocannabinol, is the most studied cannabinoid. It is a partial agonist of CB1 receptors in the brain and CB2 receptors in the body.

 It is particularly used for neuropathic pain, increasing appetite, reducing muscle spasm. Reducing the side effects of chemotherapy including neurological damage associated with it.  Since 1975, Munson AE (et al) have showed through animal testing the Anti-neoplastic activity of THC and other cannabinoids. It has taken up to now for a drug company to evaluate the herb in clinical trials, because of negative political pressure on academic institutions. Only four universities in the UK are allowed to study Cannabis. 

THC containing cannabis however useful is a strong medicine. It is not suited to all patients. It has the potential for a range of side effects. Titration is necessary for patients who are not experienced in the use of the herb, in order to avoid side effects. The side effects include: anxiety, abstract or philosophical thinking, disruption of linear memory, paranoia, dry mouth, auditory and visual hallucinations at high doses. These side effects are much less likely to happen when equal amounts of CBD are found in the cannabis used or added to the THC strain used. Although some patients will find the herb a panacea, and not notice any side effects; other will not be able to tolerate the side effects.



 Obviously, THC does not always induce side effects, its popularity as a recreational drug is based on its euphoric and sensory enhancing properties. The fact that it is both calming and stimulating, puts it potentially into the category of psychedelic; that it alters cognition and sensory perception. As a psychedelic, many people who have never tried it before may struggle at first with the altered state of consciousness it brings. Therefore, patients are most likely to use it only if they have a serious and chronic health condition and if they have tried all other options.

Many people who use the herb recreationally, especially those who have used it for many decades, could be said to be using it medicinally, whether to relax, sleep, reduce period pain, other pain, or to be in another place from normal, the same way people use alcohol. Other recreational / medical users can be seen as using the herb in an unhealthily dependent way, where they avoid reality by constantly using the herb. Many medical users feel stigmatized for their use of the herb, particularly in countries where it remains illegal, and a cultural and political stigma around its use prevails.


CBD oil has become a popular extract of the herb in the UK and around the world. Its miraculous benefits in childhood epilepsy are a major factor for the decriminalization of the herb in the USA. Although the market for it is full of businesses jumping on the bandwagon of the latest herbal panacea, it is used successfully for a range of conditions, such as epilepsy, anxiety, reducing the side effects of conventional cancer therapies, muscular- skeletal diseases caused by inflammatory injury. Despite the USA federal government not legalizing CBD or THC, they have held a medical patent on these cannabinoids and in their abstract for the patent they state that:  

“Cannabinoids have been found to have antioxidant properties, unrelated to NMDA receptor antagonism. This new-found property makes cannabinoids useful in the treatment and prophylaxis of wide variety of oxidation associated diseases, such as ischemic, age-related, inflammatory and autoimmune diseases. The cannabinoids are found to have particular application as neuroprotectants, for example in limiting neurological damage following ischemic insults, such as stroke and trauma, or in the treatment of neurodegenerative diseases, such as Alzheimer’s disease, Parkinson’s disease and HIV dementia. Nonpsychoactive cannabinoids, such as cannabidiol, are particularly advantageous to use because they avoid toxicity that is encountered with psychoactive cannabinoids at high doses useful in the method of the present invention.”



My personal journey with cannabis is that I smoked it regularly from the age of 19 -23, at which time I began to get paranoid on smoking it, and felt it restricted an emerging sense of my own spiritual path. So, for many years I had no contact with the herb at all.

18 years later I was asked if I could get hemp oil for two patients. Hemp oil is a recent euphemism for Cannabis essential oil. After researching this, I had to say that I couldn't supply this product as it was illegal. I began to study the uses of the oil in the treatment of cancer, in relieving pain and side effects of chemotherapy and radiotherapy treatments, and people attempting to cure themselves of cancer. This was mostly from following forums of oil users. I also joined the ICRS and started to study scientific papers on the subject.

 My house mate at the time had Myelofibrosis and we started to research her condition and its treatment with the oil. After much deliberation, she sourced some oil (THC: CBD ratio 1:1) and over the course of 6 weeks saw her blood counts drop dramatically showing a great benefit from the oils use. Blood tests were done on a weekly basis and improvements were immediate and sustained. She did take a large amount of oil, building up to 0.8g per day and found the side effects of fatigue and confused thinking to be strong, but temporary and ceased when she eventually lowered the dose and stopped taking it.

 The oil can be extracted using a number of different solvents, with the solvent being evaporated away, leaving a concentrated resinous oil. This is a class A drug in the UK, meaning highly illegal. It is also known as Rick Simpson oil (RSO) named after a Canadian campaigner who promoted the use of the oil widely. It is also confusingly called Hemp oil.

I attended a meeting of the Brighton Cannabis Club, and met an MS patient Clark French and an Epilepsy patient Kieron Reeves. They had decided that to get Cannabis legalized for medicinal use, they would have to start a campaigning group targeted specifically at making medical use legal first, as that is the way decriminalisation has happened in the USA and the EU. I helped them set up the United Patients Alliance (UPA) a patient advocate and campaigning group. Our first meeting was attended by Caroline Lucas MP, and Professor David Nutt, the ex-government drugs Tsar. They both spoke of the need to decriminalise medical use of the herb.

 I then introduced my UPA colleagues to Rt. Hon. Norman Baker, who at the time was the minister in charge of drug policy. We were invited to Whitehall to give a presentation to the home office and one month later Mr. Baker did make a public announcement that medical patients should not be criminalised for using the herb. Unfortunately, a liberal minister in Theresa Mays home office had little chance of turning this view into law, and shortly after he lost his seat in the commons. Norman Baker has recently agreed to become an active patron of the UPA.


What I find surprising in the herbal world is the lack of interest in this important herb from the professional bodies. I would like to see the NIMH and CPP have an active and positive stance on the decriminalisation of Cannabis for medical use. I would also expect the herb to be taught about in the degrees. After all other illegal herbs are taught about.

Functional medicine courses have modules teaching the chemistry of the herb and its therapeutic potential. It is very likely to be decriminalized for medicinal use in the UK in the next few years and I would like Herbalists to be at the vanguard of professionals able to prescribe it. 

  Copyright Haskel Adamson