This guide was created by doctors and pharmacists to give you the most fundamental knowledge about cannabis. You will learn some common terminology as well as a core understanding of what cannabis and CBD is, and how it may impact your health. If there is any specific topic you wish to learn, then please click on the headings on the side.

Otherwise, continue reading to gain new insights into this wonder plant from a scientific perspective. We may reference some studies and evidence, though this is purely to inform you of these and not to infer any medical claims.

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Cannabis has been a part of human culture and healthcare for many thousands of years. Across our planet, spanning the continent, race and religion cannabis has been used by humans for many reasons. Healing is one most commonly used for. According to some Japanese historians, cannabis was at the heart of their culture going back as far as 8000 B.C. The earliest written record of the use of cannabis comes from ancient China around 6000 B.C. when Emperor Shen-Nung used it in topicals and in teas. 


In India, cannabis has played a significant part in Indian culture. According to the ancient text The Vedas, cannabis is considered one of 5 sacred plants which is used to eliminate fear and anxiety and attain delight. In fact, anandamide (cannabinoid naturally found in humans) was named after the Sanskrit word ‘Ananda’, which translates to bliss

In Europe the Romans widely used hemp (variation of cannabis) extensively in the ‘healing arts’. In his writings the famous scholar Pliny the Elder claimed that cannabis extract was helpful for relieving discomfort.

In 1533 English King, Henry VII made hemp cultivation the law of the land. Farms of certain sizes had to dedicate a portion of land to farming hemp. The hemp was used as a key resource to transform into objects such at textiles, rope, biodegradable plastics, construction, food, and fuel. It is one of the fastest growing biomasses known and one of the earliest domesticated plants known. 

Emperor Shen-Nung holding the cannabis plant 2700 B.C

Emperor Shen-Nung holding the cannabis plant 2700 B.C

In the U.S, cannabis was legal up until the 1950s when a political campaign criminalised and rescheduled cannabis to a hard drug. This resulted in the incarceration of thousands of innocent people. In 2008 in the U.K cannabis was rescheduled to a class B, which incurs a criminal offence. 


However, in recent times advancements in the cannabis and healthcare industries have given rise to a new wave of information and innovation. More studies and clinical evidence supporting the use of medicinal cannabis has triggered reforms in drug policy. This has allowed medication such as Epidiolex to be approved for use in seizures. Technologies have been developed to increase yield and production of cannabis throughout the U.K. That is why the U.K is the world’s leading exporter of cannabis. Yet access for its population is limited. Countries like Canada and the U.S have made changes to their policy towards cannabis and as a result, are already enjoying the benefits of. 


Policy changes have given people easier access to medicinal cannabis to help with conditions such as epilepsy, pain, chronic inflammation, anxiety, MS and nerve pain. It has also made it easier, for an ever-expanding pool of research to increase, as clinicians have more access and funding, giving them better insights into how this plant improves human health. 


The cannabis black market worth billions is also being eliminated. More importantly, decriminalisation of possession has meant that people are no longer unjustly being sentenced to prison.


The economy is also something that has enjoyed a boom. For example, the state of Colorado, raised over $1 BILLION in tax revenue since 2014, just from cannabis sales. This money was used to fund over 60 projects for the people, by the people, addressing mental health, education, the environment and more.


Changes in the attitude towards cannabis can be accredited to pioneers in the industry who have used science to lead the healthcare revolution. And it is companies like ours, that promote integrity and transparency into the ever-evolving cannabis movement.


Ascension Gardens was created, by healthcare professionals. Our team of doctors, pharmacists and pharmacologists are always seeking to provide you, with all the information and guidance you need. So that you can make informed decisions about your health. We also encourage you to do your own research from reputable sites like PubMed, which hold many studies on the effects of cannabidiol (CBD) on human health. As the research expands, we will aim to bring you the latest scientific knowledge and advancements in the field of medicinal cannabis. Though we may reference evidence throughout our content, we only do so to inform you of these.

What is Cannabis?

Cannabis is a term for a whole family of plants, which include 2 distinct ‘strains’: Cannabis Sativa and Cannabis Indica. The two strains have distinct features: Sativa is taller and has long, thin leaves, whereas Indica is shorter and has short, thick leaves. The flowers are also different in appearance between these two categories and also within them. A hybrid strain is a crossbreed between Sativa and Indica, with most strains today being a form of hybrid. What determines whether a plant is Indica or Sativa or a hybrid is not just the appearance, but also what unique combination of cannabinoids each possesses. 

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Cannabinoids are a group of chemicals found in cannabis plants. There are over 100 known cannabinoids present in cannabis, with THC and CBD being the two most abundent and therefore the most researched. 

  • THC is psychoactive, meaning it gets you ‘high’
  • CBD is non-psychoactive and will not get you ‘high’

This is a very important difference between the two cannabinoids. Although studies show that they both work better together, the legal classification of THC means that it is unlawful to posess and use unless prescribed. That is why the current legal limit of THC in cannabis oil is 0.2%. 

Here are some of the other cannabinoids:

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This list is not exhaustive and we will be covering the other cannabinoids in more detail in our blog posts. We would, however, like to emphasise that all of these cannabinoids work together and complement each other. Like a good recipe that contains different ingredients in the right amount, cannabis and its strains contain these cannabinoids in different amounts which give it, its unique quality.

This synergistic effect between the cannabinoids is well researched and documented by scientists who have named this phenomenon the entourage effect. 

These cannabinoids work together by activating our endocannabinoid system (ECS) which in turn brings the body back into balance. 



As well as the cannabinoids, the cannabis plant contains another group of molecules called terpenes. They are found throughout nature and these aromatic oils are responsible for giving each cannabis strain its distinct aroma and flavour. There are over 100 terpenes, each with its own aroma and each with its own unique therapeutic properties. Further to giving off nice fumes and taste, terpenes also play a part in the entourage effect, thereby enhancing the beneficial effects of the plant. More and more research is validating the ‘entourage effect’ and it seems that terpenes play a pivotal role in optimising the therapeutic potential of medicinal cannabis. Most CBD oils lack a good terpene profile as most of it is removed during the extraction of CBD oil. 



Like terpenes, flavonoids also add to the ‘entourage effect’, thus enhancing the effect. They account for roughly 10% of the bioactive compounds found in cannabis and they add to its character by enhancing its flavour, aroma and even the pigmentation. Studies have also shown some flavonoids to be therapeutic and even anti-inflammatory such as cannaflavin. They, along with cannabinoids and terpenes are the subject of much research and investigation for therapeutic potential. 

The Endocannabinoid System (ECS)

To explain how CBD works, let us first start with the ECS. All humans and mammals have an ECS which is a network of receptors found in the central and peripheral nervous system.

Once an appropriate molecule binds to a receptor, the ECS becomes activated. There are two types of receptors:

  • cannabinoid receptor 1 (CB1)
  • cannabinoid receptor 2 (CB2).

These receptors are found in varying amounts throughout the body with CB1 primarily found in the central nervous system and CB2 spread throughout immune cells, gastrointestinal tract and peripheral nervous system.

The fact that these receptors are spread throughout key parts of the body should illustrate just how significant the ECS is, in maintaining balance within the body, a process known as homeostasis. 

Research shows us that the ECS is involved in many vital functions such as: 





Immune Function








If the ECS is under stimulated then, the body becomes less harmonised and less balanced. The body goes further from homeostasis and that’s when a variety of illness can occur. 

This system is activated without any foreign substances with our own endocannabinoids, such anandamide (bliss molecule). However, when activated by other cannabinoids such as CBD, the ECS operates on a much more efficient level.

If the ECS is under stimulated then, the body becomes less harmonised and less balanced. The body goes further from homeostasis and that’s when a variety of illness can occur. 

This system is activated without any foreign substances with our own endocannabinoids, such anandamide (bliss molecule). However, when activated by other cannabinoids such as CBD, the ECS operates on a much more efficient level.

What is medical cannabis used for?

In the UK, the Current CBPMs prescribed on the NHS are for:

Chronic Pain
Sativex (CBD+THC)

Multiple Sclerosis
Sativex (CBD+THC)

Treatment-resistant Epilepsy
Epidiolex (CBD)

N&V from Chemotherapy
Dronabinol (THC)

In the United States, over 2 million Americans smoke marijuana for medical reasons.

A common use is Pain control, others include; multiple sclerosis pain relief, Epilepsy, Parkinson’s, fibromyalgia, endometriosis, internal cystitis, Glaucoma, PTSD, Crohn's, IBS, nausea and weight loss


In the UK, Drugscience is leading Project Twenty21 which will enrol 20,000 patients that will receive medicinal cannabis at a subsidised cost. 


The study will provide the largest body of evidence into the effectiveness and tolerability of medicinal cannabis. It will also support prescribers across the country and make a strong case for NHS funding.


For more information visit Drug Science here

Route of administration


This remains the most common form of consumption among recreational and therapeutic users however it is not the safest as users may suffer from chronic cough, bronchitis and inhalation of toxic combustion products (i.e. tar, nitrosamines, carbon monoxide and ammonia).


(prescription cannabinoids, edibles, tinctures, lollipops, lozenges, nabiximols)

Prescribed CBPMs such as Sativex are consumed via this route.  Recreationally, some consumers may incorporate cannabis into baking brownies.  Effects take longer to come on (0.6-6 hours) however they last longer and are less intense as bioavailability is much lower (~15%) due to degradation in the liver.

This route Is better for patients with chronic illnesses that may need continuous relief.  Furthermore, it is much harder to control dosing for edible products.


(herbal cannabis, resin, concentrates)

There is very low absorption of THC through the rectal mucosa as THC is a hydrophobic compound and the colon’s main role lies in absorbing water and hydrophilic compounds.


Another popular method of consumption.  Cannabis extracts or oils are heated within a vape pen.  The cannabis product reaches a high enough temperature to decarboxylate the cannabinoids but not high enough to reach combustion, therefore the toxic by-products of combustion are not inhaled.

Cannabinoids reach their maximum concentration within the blood and brain through this method a few minutes after administration.  Advantages are quick relief in acute situations and high bioavailability (~25%).  Disadvantages lie with the variable amount of cannabinoids taken by the user depending on the type of oil cartridges, temperature, duration of vaporisation and duration of inhalation.  Furthermore, the effects are not as long-lasting as plasma levels of cannabinoids increase very fast and also decrease very fast.


(herbal cannabis, resin, concentrates)

Absorption through dermal patches are slow and long lasting. Peak plasma levels are reached 0.5-1.5 hours after administration and can last up to 48 hours).

Side effects & Interactions

Reactions depend on the user, strain and frequency of use. Some users may have none and others may be less fortunate.

Side effects reported include; bloodshot eyes, Dizziness, Hallucinations, dysphoria, low blood pressure, impaired motor coordination (interfering with driving), altered judgement, impaired short-term memory


THC and CBD increase levels

Frequent use increases INR



Increases THC levels



Cannabis decreases theophylline levels



CBD can increase clobazam levels


Adverse Effects

Although they’re rare there are a few:



Bronchitis can develop from smoking cannabis, usually resolves when the user stops smoking.  Vaping has fewer respiratory symptoms.


THC can cause tachycardia (fast heart rate), chronic users can develop bradycardia (slow heart rate).

Cannabis can cause changes in blood pressure.

Cannabis can increase the risk of angina.


It is recommended to avoid cannabis during pregnancy.

Heavy use during pregnancy can increase the risk of preterm birth, adverse effects on early neurodevelopment including cognitive impairment in later life and a potential decrease in foetal growth.


Adolescent users:

Demonstrated significantly smaller medial orbitofrontal and inferior parietal volumes (regions of the brain associated with higher-order cognition).

Cannabis use before 18 can lower IQ in adult life.

Cannabis use in adolescence can increase the risk of psychiatric problems in adulthood.

Long term users can exhibit deficits in memory.


Cannabis can reduce anxiety at low doses however it may increase anxiety at very high doses.

Studies suggest that people at risk of schizophrenia are at a higher risk of psychosis after prolonged cannabis use.

Cannabis dependence is estimated global prevalence is 0.23% in males and 0.14% in females.  Prevalence peaks between 20-24 years of age, and decreases with age.



Acute psychosis or other unstable psychiatric condition.



Cannabis may exacerbate arrhythmia.

Severe cardiovascular, immunological, liver, or kidney disease, especially in acute illness.